Merge 'Trigger support' from Jussi Saurio

## Trigger Support
This PR adds support for triggers:
- `CREATE TRIGGER`
- `DROP TRIGGER`
Supported
- `BEFORE/AFTER INSERT`
- `BEFORE/AFTER DELETE`
- `BEFORE/AFTER UPDATE [OF <col1,col2,col3>]`
Not supported:
- `INSTEAD OF`
- `TEMPORARY`
### Implementation details
- Triggers are executed within a new `Insn::Program` instruction. The
spec of the insn differs a bit from SQlite: we store a `Statement`
inside that instruction that we can `reset()` for every invocation.
- Like Sqlite, trigger programs take `NEW` and `OLD` rows as program
parameters.
Whenever there are triggers that would fire as the result of a DML
statement:
- `DELETE` writes the rows being deleted into a `RowSet` first.
- `UPDATE` and `INSERT` write the rows being updated into an ephemeral
table first.
### Other shit
Also added `EXPLAIN` support - the bytecode plans for trigger
subprograms are appended after the main program.
### AI disclosure
Used Cursor quite a bit for generating boilerplate code for this - you
can blame all the bad code on the AI of course 🤡
### Follow-ups:
1. ALTER TABLE ops need to rewrite the sql in the CREATE TRIGGER
statement e.g. if a column is renamed. Columns cannot be dropped if
referenced in triggers.
2. Fix weird rowid -1 fallback:
https://github.com/tursodatabase/turso/pull/3979#issuecomment-3547999449

Closes #3979

core/lib.rs

@@ -41,6 +41,7 @@ pub mod numeric;
 mod numeric;
 
 use crate::index_method::IndexMethod;
+use crate::schema::Trigger;
 use crate::storage::checksum::CHECKSUM_REQUIRED_RESERVED_BYTES;
 use crate::storage::encryption::AtomicCipherMode;
 use crate::storage::pager::{AutoVacuumMode, HeaderRef};
@@ -642,6 +643,8 @@ impl Database {
             view_transaction_states: AllViewsTxState::new(),
             metrics: RwLock::new(ConnectionMetrics::new()),
             nestedness: AtomicI32::new(0),
+            compiling_triggers: RwLock::new(Vec::new()),
+            executing_triggers: RwLock::new(Vec::new()),
             encryption_key: RwLock::new(None),
             encryption_cipher_mode: AtomicCipherMode::new(CipherMode::None),
             sync_mode: AtomicSyncMode::new(SyncMode::Full),
@@ -1167,6 +1170,11 @@ pub struct Connection {
     /// The state is integer as we may want to spawn deep nested programs (e.g. Root -[run]-> S1 -[run]-> S2 -[run]-> ...)
     /// and we need to track current nestedness depth in order to properly understand when we will reach the root back again
     nestedness: AtomicI32,
+    /// Stack of currently compiling triggers to prevent recursive trigger subprogram compilation
+    compiling_triggers: RwLock<Vec<Arc<Trigger>>>,
+    /// Stack of currently executing triggers to prevent recursive trigger execution
+    /// Only prevents the same trigger from firing again, allowing different triggers on the same table to fire
+    executing_triggers: RwLock<Vec<Arc<Trigger>>>,
     encryption_key: RwLock<Option<EncryptionKey>>,
     encryption_cipher_mode: AtomicCipherMode,
     sync_mode: AtomicSyncMode,
@@ -1212,6 +1220,52 @@ impl Connection {
     pub fn end_nested(&self) {
         self.nestedness.fetch_add(-1, Ordering::SeqCst);
     }
+
+    /// Check if a specific trigger is currently compiling (for recursive trigger prevention)
+    pub fn trigger_is_compiling(&self, trigger: impl AsRef<Trigger>) -> bool {
+        let compiling = self.compiling_triggers.read();
+        if let Some(trigger) = compiling.iter().find(|t| t.name == trigger.as_ref().name) {
+            tracing::debug!("Trigger is already compiling: {}", trigger.name);
+            return true;
+        }
+        false
+    }
+
+    pub fn start_trigger_compilation(&self, trigger: Arc<Trigger>) {
+        tracing::debug!("Starting trigger compilation: {}", trigger.name);
+        self.compiling_triggers.write().push(trigger.clone());
+    }
+
+    pub fn end_trigger_compilation(&self) {
+        tracing::debug!(
+            "Ending trigger compilation: {:?}",
+            self.compiling_triggers.read().last().map(|t| &t.name)
+        );
+        self.compiling_triggers.write().pop();
+    }
+
+    /// Check if a specific trigger is currently executing (for recursive trigger prevention)
+    pub fn is_trigger_executing(&self, trigger: impl AsRef<Trigger>) -> bool {
+        let executing = self.executing_triggers.read();
+        if let Some(trigger) = executing.iter().find(|t| t.name == trigger.as_ref().name) {
+            tracing::debug!("Trigger is already executing: {}", trigger.name);
+            return true;
+        }
+        false
+    }
+
+    pub fn start_trigger_execution(&self, trigger: Arc<Trigger>) {
+        tracing::debug!("Starting trigger execution: {}", trigger.name);
+        self.executing_triggers.write().push(trigger.clone());
+    }
+
+    pub fn end_trigger_execution(&self) {
+        tracing::debug!(
+            "Ending trigger execution: {:?}",
+            self.executing_triggers.read().last().map(|t| &t.name)
+        );
+        self.executing_triggers.write().pop();
+    }
     pub fn prepare(self: &Arc<Connection>, sql: impl AsRef<str>) -> Result<Statement> {
         if self.is_mvcc_bootstrap_connection() {
             // Never use MV store for bootstrapping - we read state directly from sqlite_schema in the DB file.
@@ -2053,6 +2107,10 @@ impl Connection {
         self.db.mvcc_enabled()
     }
 
+    pub fn mv_store(&self) -> Option<&Arc<MvStore>> {
+        self.db.mv_store.as_ref()
+    }
+
     /// Query the current value(s) of `pragma_name` associated to
     /// `pragma_value`.
     ///
@@ -2536,6 +2594,12 @@ pub struct Statement {
     busy_timeout: Option<BusyTimeout>,
 }
 
+impl std::fmt::Debug for Statement {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Statement").finish()
+    }
+}
+
 impl Drop for Statement {
     fn drop(&mut self) {
         self.reset();
@@ -2567,6 +2631,11 @@ impl Statement {
             busy_timeout: None,
         }
     }
+
+    pub fn get_trigger(&self) -> Option<Arc<Trigger>> {
+        self.program.trigger.clone()
+    }
+
     pub fn get_query_mode(&self) -> QueryMode {
         self.query_mode
     }
@@ -2881,12 +2950,8 @@ impl Statement {
 
     fn reset_internal(&mut self, max_registers: Option<usize>, max_cursors: Option<usize>) {
         // as abort uses auto_txn_cleanup value - it needs to be called before state.reset
-        self.program.abort(
-            self.mv_store.as_ref(),
-            &self.pager,
-            None,
-            &mut self.state.auto_txn_cleanup,
-        );
+        self.program
+            .abort(self.mv_store.as_ref(), &self.pager, None, &mut self.state);
         self.state.reset(max_registers, max_cursors);
         self.busy = false;
         self.busy_timeout = None;

core/schema.rs

@@ -74,6 +74,47 @@ impl Clone for View {
 /// Type alias for regular views collection
 pub type ViewsMap = HashMap<String, Arc<View>>;
 
+/// Trigger structure
+#[derive(Debug, Clone)]
+pub struct Trigger {
+    pub name: String,
+    pub sql: String,
+    pub table_name: String,
+    pub time: turso_parser::ast::TriggerTime,
+    pub event: turso_parser::ast::TriggerEvent,
+    pub for_each_row: bool,
+    pub when_clause: Option<turso_parser::ast::Expr>,
+    pub commands: Vec<turso_parser::ast::TriggerCmd>,
+    pub temporary: bool,
+}
+
+impl Trigger {
+    #[allow(clippy::too_many_arguments)]
+    pub fn new(
+        name: String,
+        sql: String,
+        table_name: String,
+        time: Option<turso_parser::ast::TriggerTime>,
+        event: turso_parser::ast::TriggerEvent,
+        for_each_row: bool,
+        when_clause: Option<turso_parser::ast::Expr>,
+        commands: Vec<turso_parser::ast::TriggerCmd>,
+        temporary: bool,
+    ) -> Self {
+        Self {
+            name,
+            sql,
+            table_name,
+            time: time.unwrap_or(turso_parser::ast::TriggerTime::Before),
+            event,
+            for_each_row,
+            when_clause,
+            commands,
+            temporary,
+        }
+    }
+}
+
 use crate::storage::btree::{BTreeCursor, CursorTrait};
 use crate::translate::collate::CollationSeq;
 use crate::translate::plan::{SelectPlan, TableReferences};
@@ -130,6 +171,9 @@ pub struct Schema {
 
     pub views: ViewsMap,
 
+    /// table_name to list of triggers
+    pub triggers: HashMap<String, VecDeque<Arc<Trigger>>>,
+
     /// table_name to list of indexes for the table
     pub indexes: HashMap<String, VecDeque<Arc<Index>>>,
     pub has_indexes: std::collections::HashSet<String>,
@@ -163,6 +207,7 @@ impl Schema {
         let materialized_view_sql = HashMap::new();
         let incremental_views = HashMap::new();
         let views: ViewsMap = HashMap::new();
+        let triggers = HashMap::new();
         let table_to_materialized_views: HashMap<String, Vec<String>> = HashMap::new();
         let incompatible_views = HashSet::new();
         Self {
@@ -171,6 +216,7 @@ impl Schema {
             materialized_view_sql,
             incremental_views,
             views,
+            triggers,
             indexes,
             has_indexes,
             indexes_enabled,
@@ -310,6 +356,72 @@ impl Schema {
         self.views.get(&name).cloned()
     }
 
+    pub fn add_trigger(&mut self, trigger: Trigger, table_name: &str) -> Result<()> {
+        self.check_object_name_conflict(&trigger.name)?;
+        let table_name = normalize_ident(table_name);
+
+        // See [Schema::add_index] for why we push to the front of the deque.
+        self.triggers
+            .entry(table_name)
+            .or_default()
+            .push_front(Arc::new(trigger));
+
+        Ok(())
+    }
+
+    pub fn remove_trigger(&mut self, name: &str) -> Result<()> {
+        let name = normalize_ident(name);
+
+        let mut removed = false;
+        for triggers_list in self.triggers.values_mut() {
+            for i in 0..triggers_list.len() {
+                let trigger = &triggers_list[i];
+                if normalize_ident(&trigger.name) == name {
+                    removed = true;
+                    triggers_list.remove(i);
+                    break;
+                }
+            }
+            if removed {
+                break;
+            }
+        }
+        if !removed {
+            return Err(crate::LimboError::ParseError(format!(
+                "no such trigger: {name}"
+            )));
+        }
+        Ok(())
+    }
+
+    pub fn get_trigger_for_table(&self, table_name: &str, name: &str) -> Option<Arc<Trigger>> {
+        let table_name = normalize_ident(table_name);
+        let name = normalize_ident(name);
+        self.triggers
+            .get(&table_name)
+            .and_then(|triggers| triggers.iter().find(|t| t.name == name).cloned())
+    }
+
+    pub fn get_triggers_for_table(
+        &self,
+        table_name: &str,
+    ) -> impl Iterator<Item = &Arc<Trigger>> + Clone {
+        let table_name = normalize_ident(table_name);
+        self.triggers
+            .get(&table_name)
+            .map(|triggers| triggers.iter())
+            .unwrap_or_default()
+    }
+
+    pub fn get_trigger(&self, name: &str) -> Option<Arc<Trigger>> {
+        let name = normalize_ident(name);
+        self.triggers
+            .values()
+            .flatten()
+            .find(|t| t.name == name)
+            .cloned()
+    }
+
     pub fn add_btree_table(&mut self, table: Arc<BTreeTable>) -> Result<()> {
         self.check_object_name_conflict(&table.name)?;
         let name = normalize_ident(&table.name);
@@ -856,6 +968,45 @@ impl Schema {
                     }
                 }
             }
+            "trigger" => {
+                use turso_parser::ast::{Cmd, Stmt};
+                use turso_parser::parser::Parser;
+
+                let sql = maybe_sql.expect("sql should be present for trigger");
+                let trigger_name = name.to_string();
+
+                let mut parser = Parser::new(sql.as_bytes());
+                let Ok(Some(Cmd::Stmt(Stmt::CreateTrigger {
+                    temporary,
+                    if_not_exists: _,
+                    trigger_name: _,
+                    time,
+                    event,
+                    tbl_name,
+                    for_each_row,
+                    when_clause,
+                    commands,
+                }))) = parser.next_cmd()
+                else {
+                    return Err(crate::LimboError::ParseError(format!(
+                        "invalid trigger sql: {sql}"
+                    )));
+                };
+                self.add_trigger(
+                    Trigger::new(
+                        trigger_name.clone(),
+                        sql.to_string(),
+                        tbl_name.name.to_string(),
+                        time,
+                        event,
+                        for_each_row,
+                        when_clause.map(|e| *e),
+                        commands,
+                        temporary,
+                    ),
+                    tbl_name.name.as_str(),
+                )?;
+            }
             _ => {}
         };
 
@@ -1198,6 +1349,16 @@ impl Clone for Schema {
             .iter()
             .map(|(name, view)| (name.clone(), Arc::new((**view).clone())))
             .collect();
+        let triggers = self
+            .triggers
+            .iter()
+            .map(|(table_name, triggers)| {
+                (
+                    table_name.clone(),
+                    triggers.iter().map(|t| Arc::new((**t).clone())).collect(),
+                )
+            })
+            .collect();
         let incompatible_views = self.incompatible_views.clone();
         Self {
             tables,
@@ -1205,6 +1366,7 @@ impl Clone for Schema {
             materialized_view_sql,
             incremental_views,
             views,
+            triggers,
             indexes,
             has_indexes: self.has_indexes.clone(),
             indexes_enabled: self.indexes_enabled,

core/storage/pager.rs

@@ -817,14 +817,14 @@ impl Pager {
 
     /// Rollback to the newest savepoint. This basically just means reading the subjournal from the start offset
     /// of the savepoint to the end of the subjournal and restoring the page images to the page cache.
-    pub fn rollback_to_newest_savepoint(&self) -> Result<()> {
+    pub fn rollback_to_newest_savepoint(&self) -> Result<bool> {
         let subjournal = self.subjournal.read();
         let Some(subjournal) = subjournal.as_ref() else {
-            return Ok(());
+            return Ok(false);
         };
         let mut savepoints = self.savepoints.write();
         let Some(savepoint) = savepoints.pop() else {
-            return Ok(());
+            return Ok(false);
         };
         let journal_start_offset = savepoint.start_offset.load(Ordering::SeqCst);
 
@@ -901,7 +901,7 @@ impl Pager {
 
         self.page_cache.write().truncate(db_size as usize)?;
 
-        Ok(())
+        Ok(true)
     }
 
     #[cfg(feature = "test_helper")]

core/translate/delete.rs

@@ -2,13 +2,16 @@ use crate::schema::{Schema, Table};
 use crate::translate::emitter::{emit_program, Resolver};
 use crate::translate::expr::process_returning_clause;
 use crate::translate::optimizer::optimize_plan;
-use crate::translate::plan::{DeletePlan, Operation, Plan};
+use crate::translate::plan::{
+    DeletePlan, JoinOrderMember, Operation, Plan, QueryDestination, ResultSetColumn, SelectPlan,
+};
 use crate::translate::planner::{parse_limit, parse_where};
+use crate::translate::trigger_exec::has_relevant_triggers_type_only;
 use crate::util::normalize_ident;
 use crate::vdbe::builder::{ProgramBuilder, ProgramBuilderOpts};
 use crate::Result;
 use std::sync::Arc;
-use turso_parser::ast::{Expr, Limit, QualifiedName, ResultColumn};
+use turso_parser::ast::{Expr, Limit, QualifiedName, ResultColumn, TriggerEvent};
 
 use super::plan::{ColumnUsedMask, JoinedTable, TableReferences};
 
@@ -93,6 +96,8 @@ pub fn prepare_delete_plan(
         );
     }
 
+    let btree_table_for_triggers = table.btree();
+
     let table = if let Some(table) = table.virtual_table() {
         Table::Virtual(table.clone())
     } else if let Some(table) = table.btree() {
@@ -130,7 +135,72 @@ pub fn prepare_delete_plan(
     let (resolved_limit, resolved_offset) =
         limit.map_or(Ok((None, None)), |l| parse_limit(l, connection))?;
 
-    let plan = DeletePlan {
+    // Check if there are DELETE triggers. If so, we need to materialize the write set into a RowSet first.
+    // This is done in SQLite for all DELETE triggers on the affected table even if the trigger would not have an impact
+    // on the target table -- presumably due to lack of static analysis capabilities to determine whether it's safe
+    // to skip the rowset materialization.
+    let has_delete_triggers = btree_table_for_triggers
+        .as_ref()
+        .map(|bt| has_relevant_triggers_type_only(schema, TriggerEvent::Delete, None, bt))
+        .unwrap_or(false);
+
+    if has_delete_triggers {
+        // Create a SelectPlan that materializes rowids into a RowSet
+        let rowid_internal_id = table_references
+            .joined_tables()
+            .first()
+            .unwrap()
+            .internal_id;
+        let rowset_reg = program.alloc_register();
+
+        let rowset_plan = SelectPlan {
+            table_references: table_references.clone(),
+            result_columns: vec![ResultSetColumn {
+                expr: Expr::RowId {
+                    database: None,
+                    table: rowid_internal_id,
+                },
+                alias: None,
+                contains_aggregates: false,
+            }],
+            where_clause: where_predicates,
+            group_by: None,
+            order_by: vec![],
+            aggregates: vec![],
+            limit: resolved_limit,
+            query_destination: QueryDestination::RowSet { rowset_reg },
+            join_order: table_references
+                .joined_tables()
+                .iter()
+                .enumerate()
+                .map(|(i, t)| JoinOrderMember {
+                    table_id: t.internal_id,
+                    original_idx: i,
+                    is_outer: false,
+                })
+                .collect(),
+            offset: resolved_offset,
+            contains_constant_false_condition: false,
+            distinctness: super::plan::Distinctness::NonDistinct,
+            values: vec![],
+            window: None,
+            non_from_clause_subqueries: vec![],
+        };
+
+        Ok(Plan::Delete(DeletePlan {
+            table_references,
+            result_columns,
+            where_clause: vec![],
+            order_by: vec![],
+            limit: None,
+            offset: None,
+            contains_constant_false_condition: false,
+            indexes,
+            rowset_plan: Some(rowset_plan),
+            rowset_reg: Some(rowset_reg),
+        }))
+    } else {
+        Ok(Plan::Delete(DeletePlan {
             table_references,
             result_columns,
             where_clause: where_predicates,
@@ -139,9 +209,10 @@ pub fn prepare_delete_plan(
             offset: resolved_offset,
             contains_constant_false_condition: false,
             indexes,
-    };
-
-    Ok(Plan::Delete(plan))
+            rowset_plan: None,
+            rowset_reg: None,
+        }))
+    }
 }
 
 fn estimate_num_instructions(plan: &DeletePlan) -> usize {

core/translate/insert.rs

@@ -1,7 +1,8 @@
 use std::num::NonZeroUsize;
 use std::sync::Arc;
 use turso_parser::ast::{
-    self, Expr, InsertBody, OneSelect, QualifiedName, ResolveType, ResultColumn, Upsert, UpsertDo,
+    self, Expr, InsertBody, OneSelect, QualifiedName, ResolveType, ResultColumn, TriggerEvent,
+    TriggerTime, Upsert, UpsertDo,
 };
 
 use crate::error::{
@@ -24,6 +25,7 @@ use crate::translate::plan::{
     ColumnUsedMask, JoinedTable, Operation, ResultSetColumn, TableReferences,
 };
 use crate::translate::planner::ROWID_STRS;
+use crate::translate::trigger_exec::{fire_trigger, get_relevant_triggers_type_and_time};
 use crate::translate::upsert::{
     collect_set_clauses_for_upsert, emit_upsert, resolve_upsert_target, ResolvedUpsertTarget,
 };
@@ -45,6 +47,7 @@ use super::emitter::Resolver;
 use super::expr::{translate_expr, translate_expr_no_constant_opt, NoConstantOptReason};
 use super::plan::QueryDestination;
 use super::select::translate_select;
+use super::trigger_exec::{has_relevant_triggers_type_only, TriggerContext};
 
 /// Validate anything with this insert statement that should throw an early parse error
 fn validate(table_name: &str, resolver: &Resolver, table: &Table) -> Result<()> {
@@ -316,6 +319,40 @@ pub fn translate_insert(
         init_autoincrement(&mut program, &mut ctx, resolver)?;
     }
 
+    // Fire BEFORE INSERT triggers
+
+    let relevant_before_triggers = get_relevant_triggers_type_and_time(
+        resolver.schema,
+        TriggerEvent::Insert,
+        TriggerTime::Before,
+        None,
+        &btree_table,
+    );
+    let has_relevant_before_triggers = relevant_before_triggers.clone().count() > 0;
+    if has_relevant_before_triggers {
+        // Build NEW registers: for rowid alias columns, use the rowid register; otherwise use column register
+        let new_registers: Vec<usize> = insertion
+            .col_mappings
+            .iter()
+            .map(|col_mapping| {
+                if col_mapping.column.is_rowid_alias() {
+                    insertion.key_register()
+                } else {
+                    col_mapping.register
+                }
+            })
+            .chain(std::iter::once(insertion.key_register()))
+            .collect();
+        let trigger_ctx = TriggerContext::new(
+            btree_table.clone(),
+            Some(new_registers),
+            None, // No OLD for INSERT
+        );
+        for trigger in relevant_before_triggers {
+            fire_trigger(&mut program, resolver, trigger, &trigger_ctx, connection)?;
+        }
+    }
+
     if has_user_provided_rowid {
         let must_be_int_label = program.allocate_label();
 
@@ -427,6 +464,42 @@ pub fn translate_insert(
         table_name: table_name.to_string(),
     });
 
+    // Fire AFTER INSERT triggers
+    let relevant_after_triggers = get_relevant_triggers_type_and_time(
+        resolver.schema,
+        TriggerEvent::Insert,
+        TriggerTime::After,
+        None,
+        &btree_table,
+    );
+    let has_relevant_after_triggers = relevant_after_triggers.clone().count() > 0;
+    if has_relevant_after_triggers {
+        // Build NEW registers: for rowid alias columns, use the rowid register; otherwise use column register
+        let new_registers_after: Vec<usize> = insertion
+            .col_mappings
+            .iter()
+            .map(|col_mapping| {
+                if col_mapping.column.is_rowid_alias() {
+                    insertion.key_register()
+                } else {
+                    col_mapping.register
+                }
+            })
+            .chain(std::iter::once(insertion.key_register()))
+            .collect();
+        let trigger_ctx_after =
+            TriggerContext::new(btree_table.clone(), Some(new_registers_after), None);
+        for trigger in relevant_after_triggers {
+            fire_trigger(
+                &mut program,
+                resolver,
+                trigger,
+                &trigger_ctx_after,
+                connection,
+            )?;
+        }
+    }
+
     if has_fks {
         // After the row is actually present, repair deferred counters for children referencing this NEW parent key.
         // For REPLACE: delete increments counters above; the insert path should try to repay
@@ -1069,6 +1142,7 @@ fn bind_insert(
     }
     match on_conflict {
         ResolveType::Ignore => {
+            program.set_resolve_type(ResolveType::Ignore);
             upsert.replace(Box::new(ast::Upsert {
                 do_clause: UpsertDo::Nothing,
                 index: None,
@@ -1163,6 +1237,14 @@ fn init_source_emission<'a>(
             );
         }
     }
+    // Check if INSERT triggers exist - if so, we need to use ephemeral table for VALUES with more than one row
+    let has_insert_triggers = has_relevant_triggers_type_only(
+        resolver.schema,
+        TriggerEvent::Insert,
+        None,
+        ctx.table.as_ref(),
+    );
+
     let (num_values, cursor_id) = match body {
         InsertBody::Select(select, _) => {
             // Simple common case of INSERT INTO <table> VALUES (...) without compounds.
@@ -1221,7 +1303,7 @@ fn init_source_emission<'a>(
                  ** of the tables being read by the SELECT statement.  Also use a
                  ** temp table in the case of row triggers.
                  */
-                if program.is_table_open(table) {
+                if program.is_table_open(table) || has_insert_triggers {
                     let temp_cursor_id =
                         program.alloc_cursor_id(CursorType::BTreeTable(ctx.table.clone()));
                     ctx.temp_table_ctx = Some(TempTableCtx {

core/translate/mod.rs

@@ -35,6 +35,8 @@ pub(crate) mod schema;
 pub(crate) mod select;
 pub(crate) mod subquery;
 pub(crate) mod transaction;
+pub(crate) mod trigger;
+pub(crate) mod trigger_exec;
 pub(crate) mod update;
 pub(crate) mod upsert;
 mod values;
@@ -169,7 +171,40 @@ pub fn translate_inner(
             program,
             connection,
         )?,
-        ast::Stmt::CreateTrigger { .. } => bail_parse_error!("CREATE TRIGGER not supported yet"),
+        ast::Stmt::CreateTrigger {
+            temporary,
+            if_not_exists,
+            trigger_name,
+            time,
+            event,
+            tbl_name,
+            for_each_row,
+            when_clause,
+            commands,
+        } => {
+            // Reconstruct SQL for storage
+            let sql = trigger::create_trigger_to_sql(
+                temporary,
+                if_not_exists,
+                &trigger_name,
+                time,
+                &event,
+                &tbl_name,
+                for_each_row,
+                when_clause.as_deref(),
+                &commands,
+            );
+            trigger::translate_create_trigger(
+                trigger_name,
+                resolver,
+                temporary,
+                if_not_exists,
+                time,
+                tbl_name,
+                program,
+                sql,
+            )?
+        }
         ast::Stmt::CreateView {
             view_name,
             select,
@@ -232,7 +267,15 @@ pub fn translate_inner(
             if_exists,
             tbl_name,
         } => translate_drop_table(tbl_name, resolver, if_exists, program, connection)?,
-        ast::Stmt::DropTrigger { .. } => bail_parse_error!("DROP TRIGGER not supported yet"),
+        ast::Stmt::DropTrigger {
+            if_exists,
+            trigger_name,
+        } => trigger::translate_drop_trigger(
+            resolver.schema,
+            trigger_name.name.as_str(),
+            if_exists,
+            program,
+        )?,
         ast::Stmt::DropView {
             if_exists,
             view_name,

core/translate/optimizer/mod.rs

@@ -1,7 +1,7 @@
 use std::{
     cell::RefCell,
     cmp::Ordering,
-    collections::{HashMap, VecDeque},
+    collections::{HashMap, HashSet, VecDeque},
     sync::Arc,
 };
 
@@ -13,7 +13,7 @@ use join::{compute_best_join_order, BestJoinOrderResult};
 use lift_common_subexpressions::lift_common_subexpressions_from_binary_or_terms;
 use order::{compute_order_target, plan_satisfies_order_target, EliminatesSortBy};
 use turso_ext::{ConstraintInfo, ConstraintUsage};
-use turso_parser::ast::{self, Expr, SortOrder};
+use turso_parser::ast::{self, Expr, SortOrder, TriggerEvent};
 
 use crate::{
     schema::{BTreeTable, Index, IndexColumn, Schema, Table, ROWID_SENTINEL},
@@ -27,6 +27,7 @@ use crate::{
             ColumnUsedMask, IndexMethodQuery, NonFromClauseSubquery, OuterQueryReference,
             QueryDestination, ResultSetColumn, Scan, SeekKeyComponent,
         },
+        trigger_exec::has_relevant_triggers_type_only,
     },
     types::SeekOp,
     util::{
@@ -118,6 +119,10 @@ fn optimize_delete_plan(plan: &mut DeletePlan, schema: &Schema) -> Result<()> {
         return Ok(());
     }
 
+    if let Some(rowset_plan) = plan.rowset_plan.as_mut() {
+        optimize_select_plan(rowset_plan, schema)?;
+    }
+
     let _ = optimize_table_access(
         schema,
         &mut plan.result_columns,
@@ -161,14 +166,31 @@ fn optimize_update_plan(
 
     let table_ref = &mut plan.table_references.joined_tables_mut()[0];
 
-    // An ephemeral table is required if the UPDATE modifies any column that is present in the key of the
-    // btree used to iterate over the table.
+    // An ephemeral table is required if:
+    // 1. The UPDATE modifies any column that is present in the key of the btree used to iterate over the table.
     //    For regular table scans or seeks, this is just the rowid or the rowid alias column (INTEGER PRIMARY KEY)
     //    For index scans and seeks, this is any column in the index used.
+    // 2. There are UPDATE triggers on the table. This is done in SQLite for all UPDATE triggers on
+    //    the affected table even if the trigger would not have an impact on the target table --
+    //    presumably due to lack of static analysis capabilities to determine whether it's safe
+    //    to skip the rowset materialization.
     let requires_ephemeral_table = 'requires: {
-        let Some(btree_table) = table_ref.table.btree() else {
+        let Some(btree_table_arc) = table_ref.table.btree() else {
             break 'requires false;
         };
+        let btree_table = btree_table_arc.as_ref();
+
+        // Check if there are UPDATE triggers
+        let updated_cols: HashSet<usize> = plan.set_clauses.iter().map(|(i, _)| *i).collect();
+        if has_relevant_triggers_type_only(
+            schema,
+            TriggerEvent::Update,
+            Some(&updated_cols),
+            btree_table,
+        ) {
+            break 'requires true;
+        }
+
         let Some(index) = table_ref.op.index() else {
             let rowid_alias_used = plan.set_clauses.iter().fold(false, |accum, (idx, _)| {
                 accum || (*idx != ROWID_SENTINEL && btree_table.columns[*idx].is_rowid_alias())
@@ -198,10 +220,11 @@ fn optimize_update_plan(
     add_ephemeral_table_to_update_plan(program, plan)
 }
 
-/// An ephemeral table is required if the UPDATE modifies any column that is present in the key of the
-/// btree used to iterate over the table.
+/// An ephemeral table is required if:
+/// 1. The UPDATE modifies any column that is present in the key of the btree used to iterate over the table.
 ///    For regular table scans or seeks, the key is the rowid or the rowid alias column (INTEGER PRIMARY KEY).
 ///    For index scans and seeks, the key is any column in the index used.
+/// 2. There are UPDATE triggers on the table (SQLite always uses ephemeral tables when triggers exist).
 ///
 /// The ephemeral table will accumulate all the rowids of the rows that are affected by the UPDATE,
 /// and then the temp table will be iterated over and the actual row updates performed.

core/translate/plan.rs

@@ -259,6 +259,12 @@ pub enum QueryDestination {
         /// The number of registers that hold the result of the subquery.
         num_regs: usize,
     },
+    /// The results of the query are stored in a RowSet (for DELETE operations with triggers).
+    /// Rowids are added to the RowSet using RowSetAdd, then read back using RowSetRead.
+    RowSet {
+        /// The register that holds the RowSet object.
+        rowset_reg: usize,
+    },
     /// Decision made at some point after query plan construction.
     Unset,
 }
@@ -474,6 +480,11 @@ pub struct DeletePlan {
     pub contains_constant_false_condition: bool,
     /// Indexes that must be updated by the delete operation.
     pub indexes: Vec<Arc<Index>>,
+    /// If there are DELETE triggers, materialize rowids into a RowSet first.
+    /// This ensures triggers see a stable set of rows to delete.
+    pub rowset_plan: Option<SelectPlan>,
+    /// Register ID for the RowSet (if rowset_plan is Some)
+    pub rowset_reg: Option<usize>,
 }
 
 #[derive(Debug, Clone)]
@@ -1004,10 +1015,10 @@ impl JoinedTable {
                         } else {
                             CursorType::BTreeTable(btree.clone())
                         };
-                    Some(
-                        program
-                            .alloc_cursor_id_keyed(CursorKey::table(self.internal_id), cursor_type),
-                    )
+                    Some(program.alloc_cursor_id_keyed_if_not_exists(
+                        CursorKey::table(self.internal_id),
+                        cursor_type,
+                    ))
                 };
 
                 let index_cursor_id = index

core/translate/result_row.rs

@@ -160,6 +160,18 @@ pub fn emit_result_row_and_limit(
                 extra_amount: num_regs - 1,
             });
         }
+        QueryDestination::RowSet { rowset_reg } => {
+            // For RowSet, we add the rowid (which should be the only result column) to the RowSet
+            assert_eq!(
+                plan.result_columns.len(),
+                1,
+                "RowSet should only have one result column (rowid)"
+            );
+            program.emit_insn(Insn::RowSetAdd {
+                rowset_reg: *rowset_reg,
+                value_reg: result_columns_start_reg,
+            });
+        }
         QueryDestination::Unset => unreachable!("Unset query destination should not be reached"),
     }
 

core/translate/schema.rs

@@ -307,6 +307,7 @@ pub enum SchemaEntryType {
     Table,
     Index,
     View,
+    Trigger,
 }
 
 impl SchemaEntryType {
@@ -315,6 +316,7 @@ impl SchemaEntryType {
             SchemaEntryType::Table => "table",
             SchemaEntryType::Index => "index",
             SchemaEntryType::View => "view",
+            SchemaEntryType::Trigger => "trigger",
         }
     }
 }
@@ -677,7 +679,7 @@ pub fn translate_drop_table(
     let table_reg =
         program.emit_string8_new_reg(normalize_ident(tbl_name.name.as_str()).to_string()); //  r3
     program.mark_last_insn_constant();
-    let table_type = program.emit_string8_new_reg("trigger".to_string()); //  r4
+    let _table_type = program.emit_string8_new_reg("trigger".to_string()); //  r4
     program.mark_last_insn_constant();
     let row_id_reg = program.alloc_register(); //  r5
 
@@ -692,7 +694,7 @@ pub fn translate_drop_table(
         db: 0,
     });
 
-    //  1. Remove all entries from the schema table related to the table we are dropping, except for triggers
+    //  1. Remove all entries from the schema table related to the table we are dropping (including triggers)
     //  loop to beginning of schema table
     let end_metadata_label = program.allocate_label();
     let metadata_loop = program.allocate_label();
@@ -716,18 +718,6 @@ pub fn translate_drop_table(
         flags: CmpInsFlags::default(),
         collation: program.curr_collation(),
     });
-    program.emit_column_or_rowid(
-        sqlite_schema_cursor_id_0,
-        0,
-        table_name_and_root_page_register,
-    );
-    program.emit_insn(Insn::Eq {
-        lhs: table_name_and_root_page_register,
-        rhs: table_type,
-        target_pc: next_label,
-        flags: CmpInsFlags::default(),
-        collation: program.curr_collation(),
-    });
     program.emit_insn(Insn::RowId {
         cursor_id: sqlite_schema_cursor_id_0,
         dest: row_id_reg,

core/translate/trigger.rs

@@ -0,0 +1,293 @@
+use crate::translate::emitter::Resolver;
+use crate::translate::schema::{emit_schema_entry, SchemaEntryType, SQLITE_TABLEID};
+use crate::translate::ProgramBuilder;
+use crate::translate::ProgramBuilderOpts;
+use crate::util::normalize_ident;
+use crate::vdbe::builder::CursorType;
+use crate::vdbe::insn::{Cookie, Insn};
+use crate::{bail_parse_error, Result};
+use turso_parser::ast::{self, QualifiedName};
+
+/// Reconstruct SQL string from CREATE TRIGGER AST
+#[allow(clippy::too_many_arguments)]
+pub(crate) fn create_trigger_to_sql(
+    temporary: bool,
+    if_not_exists: bool,
+    trigger_name: &QualifiedName,
+    time: Option<ast::TriggerTime>,
+    event: &ast::TriggerEvent,
+    tbl_name: &QualifiedName,
+    for_each_row: bool,
+    when_clause: Option<&ast::Expr>,
+    commands: &[ast::TriggerCmd],
+) -> String {
+    let mut sql = String::new();
+    sql.push_str("CREATE");
+    if temporary {
+        sql.push_str(" TEMP");
+    }
+    sql.push_str(" TRIGGER");
+    if if_not_exists {
+        sql.push_str(" IF NOT EXISTS");
+    }
+    sql.push(' ');
+    sql.push_str(trigger_name.name.as_str());
+    sql.push(' ');
+
+    if let Some(t) = time {
+        match t {
+            ast::TriggerTime::Before => sql.push_str("BEFORE "),
+            ast::TriggerTime::After => sql.push_str("AFTER "),
+            ast::TriggerTime::InsteadOf => sql.push_str("INSTEAD OF "),
+        }
+    }
+
+    match event {
+        ast::TriggerEvent::Delete => sql.push_str("DELETE"),
+        ast::TriggerEvent::Insert => sql.push_str("INSERT"),
+        ast::TriggerEvent::Update => sql.push_str("UPDATE"),
+        ast::TriggerEvent::UpdateOf(cols) => {
+            sql.push_str("UPDATE OF ");
+            for (i, col) in cols.iter().enumerate() {
+                if i > 0 {
+                    sql.push_str(", ");
+                }
+                sql.push_str(col.as_str());
+            }
+        }
+    }
+
+    sql.push_str(" ON ");
+    sql.push_str(tbl_name.name.as_str());
+    if for_each_row {
+        sql.push_str(" FOR EACH ROW");
+    }
+
+    if let Some(when) = when_clause {
+        sql.push_str(" WHEN ");
+        sql.push_str(&when.to_string());
+    }
+
+    sql.push_str(" BEGIN");
+    for cmd in commands {
+        sql.push(' ');
+        sql.push_str(&cmd.to_string());
+        sql.push(';');
+    }
+    sql.push_str(" END");
+
+    sql
+}
+
+/// Translate CREATE TRIGGER statement
+#[allow(clippy::too_many_arguments)]
+pub fn translate_create_trigger(
+    trigger_name: QualifiedName,
+    resolver: &Resolver,
+    temporary: bool,
+    if_not_exists: bool,
+    time: Option<ast::TriggerTime>,
+    tbl_name: QualifiedName,
+    mut program: ProgramBuilder,
+    sql: String,
+) -> Result<ProgramBuilder> {
+    program.begin_write_operation();
+    let normalized_trigger_name = normalize_ident(trigger_name.name.as_str());
+    let normalized_table_name = normalize_ident(tbl_name.name.as_str());
+
+    // Check if trigger already exists
+    if resolver
+        .schema
+        .get_trigger_for_table(&normalized_table_name, &normalized_trigger_name)
+        .is_some()
+    {
+        if if_not_exists {
+            return Ok(program);
+        }
+        bail_parse_error!("Trigger {} already exists", normalized_trigger_name);
+    }
+
+    // Verify the table exists
+    if resolver.schema.get_table(&normalized_table_name).is_none() {
+        bail_parse_error!("no such table: {}", normalized_table_name);
+    }
+
+    if time
+        .as_ref()
+        .is_some_and(|t| *t == ast::TriggerTime::InsteadOf)
+    {
+        bail_parse_error!("INSTEAD OF triggers are not supported yet");
+    }
+
+    if temporary {
+        bail_parse_error!("TEMPORARY triggers are not supported yet");
+    }
+
+    let opts = ProgramBuilderOpts {
+        num_cursors: 1,
+        approx_num_insns: 30,
+        approx_num_labels: 1,
+    };
+    program.extend(&opts);
+
+    // Open cursor to sqlite_schema table
+    let table = resolver.schema.get_btree_table(SQLITE_TABLEID).unwrap();
+    let sqlite_schema_cursor_id = program.alloc_cursor_id(CursorType::BTreeTable(table.clone()));
+    program.emit_insn(Insn::OpenWrite {
+        cursor_id: sqlite_schema_cursor_id,
+        root_page: 1i64.into(),
+        db: 0,
+    });
+
+    // Add the trigger entry to sqlite_schema
+    emit_schema_entry(
+        &mut program,
+        resolver,
+        sqlite_schema_cursor_id,
+        None, // cdc_table_cursor_id, no cdc for triggers
+        SchemaEntryType::Trigger,
+        &normalized_trigger_name,
+        &normalized_table_name,
+        0, // triggers don't have a root page
+        Some(sql.clone()),
+    )?;
+
+    // Update schema version
+    program.emit_insn(Insn::SetCookie {
+        db: 0,
+        cookie: Cookie::SchemaVersion,
+        value: (resolver.schema.schema_version + 1) as i32,
+        p5: 0,
+    });
+
+    // Parse schema to load the new trigger
+    program.emit_insn(Insn::ParseSchema {
+        db: sqlite_schema_cursor_id,
+        where_clause: Some(format!("name = '{normalized_trigger_name}'")),
+    });
+
+    Ok(program)
+}
+
+/// Translate DROP TRIGGER statement
+pub fn translate_drop_trigger(
+    schema: &crate::schema::Schema,
+    trigger_name: &str,
+    if_exists: bool,
+    mut program: ProgramBuilder,
+) -> Result<ProgramBuilder> {
+    program.begin_write_operation();
+    let normalized_trigger_name = normalize_ident(trigger_name);
+
+    // Check if trigger exists
+    if schema.get_trigger(&normalized_trigger_name).is_none() {
+        if if_exists {
+            return Ok(program);
+        }
+        bail_parse_error!("no such trigger: {}", normalized_trigger_name);
+    }
+
+    let opts = ProgramBuilderOpts {
+        num_cursors: 1,
+        approx_num_insns: 30,
+        approx_num_labels: 1,
+    };
+    program.extend(&opts);
+
+    // Open cursor to sqlite_schema table
+    let table = schema.get_btree_table(SQLITE_TABLEID).unwrap();
+    let sqlite_schema_cursor_id = program.alloc_cursor_id(CursorType::BTreeTable(table.clone()));
+    program.emit_insn(Insn::OpenWrite {
+        cursor_id: sqlite_schema_cursor_id,
+        root_page: 1i64.into(),
+        db: 0,
+    });
+
+    let search_loop_label = program.allocate_label();
+    let skip_non_trigger_label = program.allocate_label();
+    let done_label = program.allocate_label();
+    let rewind_done_label = program.allocate_label();
+
+    // Find and delete the trigger from sqlite_schema
+    program.emit_insn(Insn::Rewind {
+        cursor_id: sqlite_schema_cursor_id,
+        pc_if_empty: rewind_done_label,
+    });
+
+    program.preassign_label_to_next_insn(search_loop_label);
+
+    // Check if this is the trigger we're looking for
+    // sqlite_schema columns: type, name, tbl_name, rootpage, sql
+    // Column 0: type (should be "trigger")
+    // Column 1: name (should match trigger_name)
+    let type_reg = program.alloc_register();
+    let name_reg = program.alloc_register();
+    program.emit_insn(Insn::Column {
+        cursor_id: sqlite_schema_cursor_id,
+        column: 0,
+        dest: type_reg,
+        default: None,
+    });
+    program.emit_insn(Insn::Column {
+        cursor_id: sqlite_schema_cursor_id,
+        column: 1,
+        dest: name_reg,
+        default: None,
+    });
+
+    // Check if type == "trigger"
+    let type_str_reg = program.emit_string8_new_reg("trigger".to_string());
+    program.emit_insn(Insn::Ne {
+        lhs: type_reg,
+        rhs: type_str_reg,
+        target_pc: skip_non_trigger_label,
+        flags: crate::vdbe::insn::CmpInsFlags::default(),
+        collation: program.curr_collation(),
+    });
+
+    // Check if name matches
+    let trigger_name_str_reg = program.emit_string8_new_reg(normalized_trigger_name.clone());
+    program.emit_insn(Insn::Ne {
+        lhs: name_reg,
+        rhs: trigger_name_str_reg,
+        target_pc: skip_non_trigger_label,
+        flags: crate::vdbe::insn::CmpInsFlags::default(),
+        collation: program.curr_collation(),
+    });
+
+    // Found it! Delete the row
+    program.emit_insn(Insn::Delete {
+        cursor_id: sqlite_schema_cursor_id,
+        table_name: SQLITE_TABLEID.to_string(),
+        is_part_of_update: false,
+    });
+    program.emit_insn(Insn::Goto {
+        target_pc: done_label,
+    });
+
+    program.preassign_label_to_next_insn(skip_non_trigger_label);
+    // Continue to next row
+    program.emit_insn(Insn::Next {
+        cursor_id: sqlite_schema_cursor_id,
+        pc_if_next: search_loop_label,
+    });
+
+    program.preassign_label_to_next_insn(done_label);
+
+    program.preassign_label_to_next_insn(rewind_done_label);
+
+    // Update schema version
+    program.emit_insn(Insn::SetCookie {
+        db: 0,
+        cookie: Cookie::SchemaVersion,
+        value: (schema.schema_version + 1) as i32,
+        p5: 0,
+    });
+
+    program.emit_insn(Insn::DropTrigger {
+        db: 0,
+        trigger_name: normalized_trigger_name.clone(),
+    });
+
+    Ok(program)
+}

core/translate/trigger_exec.rs

@@ -0,0 +1,812 @@
+use crate::schema::{BTreeTable, Trigger};
+use crate::translate::emitter::Resolver;
+use crate::translate::expr::translate_expr;
+use crate::translate::{translate_inner, ProgramBuilder, ProgramBuilderOpts};
+use crate::util::normalize_ident;
+use crate::vdbe::insn::Insn;
+use crate::{bail_parse_error, QueryMode, Result, Statement};
+use parking_lot::RwLock;
+use std::collections::HashSet;
+use std::num::NonZero;
+use std::sync::Arc;
+use turso_parser::ast::{self, Expr, TriggerEvent, TriggerTime};
+
+/// Context for trigger execution
+#[derive(Debug)]
+pub struct TriggerContext {
+    /// Table the trigger is attached to
+    pub table: Arc<BTreeTable>,
+    /// NEW row registers (for INSERT/UPDATE). The last element is always the rowid.
+    pub new_registers: Option<Vec<usize>>,
+    /// OLD row registers (for UPDATE/DELETE). The last element is always the rowid.
+    pub old_registers: Option<Vec<usize>>,
+}
+
+impl TriggerContext {
+    pub fn new(
+        table: Arc<BTreeTable>,
+        new_registers: Option<Vec<usize>>,
+        old_registers: Option<Vec<usize>>,
+    ) -> Self {
+        Self {
+            table,
+            new_registers,
+            old_registers,
+        }
+    }
+}
+
+#[derive(Debug)]
+struct ParamMap(Vec<NonZero<usize>>);
+
+impl ParamMap {
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+}
+
+/// Context for compiling trigger subprograms - maps NEW/OLD to parameter indices
+#[derive(Debug)]
+struct TriggerSubprogramContext {
+    /// Map from column index to parameter index for NEW values (1-indexed)
+    new_param_map: Option<ParamMap>,
+    /// Map from column index to parameter index for OLD values (1-indexed)
+    old_param_map: Option<ParamMap>,
+    table: Arc<BTreeTable>,
+}
+
+impl TriggerSubprogramContext {
+    pub fn get_new_param(&self, idx: usize) -> Option<NonZero<usize>> {
+        self.new_param_map
+            .as_ref()
+            .and_then(|map| map.0.get(idx).copied())
+    }
+
+    pub fn get_new_rowid_param(&self) -> Option<NonZero<usize>> {
+        self.new_param_map
+            .as_ref()
+            .and_then(|map| map.0.last().copied())
+    }
+
+    pub fn get_old_param(&self, idx: usize) -> Option<NonZero<usize>> {
+        self.old_param_map
+            .as_ref()
+            .and_then(|map| map.0.get(idx).copied())
+    }
+
+    pub fn get_old_rowid_param(&self) -> Option<NonZero<usize>> {
+        self.old_param_map
+            .as_ref()
+            .and_then(|map| map.0.last().copied())
+    }
+}
+
+/// Rewrite NEW and OLD references in trigger expressions to use Variable instructions (parameters)
+fn rewrite_trigger_expr_for_subprogram(
+    expr: &mut ast::Expr,
+    table: &BTreeTable,
+    ctx: &TriggerSubprogramContext,
+) -> Result<()> {
+    use crate::translate::expr::walk_expr_mut;
+    use crate::translate::expr::WalkControl;
+
+    walk_expr_mut(expr, &mut |e: &mut ast::Expr| -> Result<WalkControl> {
+        match e {
+            Expr::Qualified(ns, col) | Expr::DoublyQualified(_, ns, col) => {
+                let ns = normalize_ident(ns.as_str());
+                let col = normalize_ident(col.as_str());
+
+                // Handle NEW.column references
+                if ns.eq_ignore_ascii_case("new") {
+                    if let Some(new_params) = &ctx.new_param_map {
+                        // Check if this is a rowid alias column first
+                        if let Some((idx, col_def)) = table.get_column(&col) {
+                            if col_def.is_rowid_alias() {
+                                // Rowid alias columns map to the rowid parameter, not the column register
+                                *e = Expr::Variable(format!(
+                                    "{}",
+                                    ctx.get_new_rowid_param()
+                                        .expect("NEW parameters must be provided")
+                                ));
+                                return Ok(WalkControl::Continue);
+                            }
+                            if idx < new_params.len() {
+                                *e = Expr::Variable(format!(
+                                    "{}",
+                                    ctx.get_new_param(idx)
+                                        .expect("NEW parameters must be provided")
+                                        .get()
+                                ));
+                                return Ok(WalkControl::Continue);
+                            } else {
+                                crate::bail_parse_error!("no such column in NEW: {}", col);
+                            }
+                        }
+                        // Handle NEW.rowid
+                        if crate::translate::planner::ROWID_STRS
+                            .iter()
+                            .any(|s| s.eq_ignore_ascii_case(&col))
+                        {
+                            *e = Expr::Variable(format!(
+                                "{}",
+                                ctx.get_new_rowid_param()
+                                    .expect("NEW parameters must be provided")
+                            ));
+                            return Ok(WalkControl::Continue);
+                        }
+                        bail_parse_error!("no such column in NEW: {}", col);
+                    } else {
+                        bail_parse_error!(
+                            "NEW references are only valid in INSERT and UPDATE triggers"
+                        );
+                    }
+                }
+
+                // Handle OLD.column references
+                if ns.eq_ignore_ascii_case("old") {
+                    if let Some(old_params) = &ctx.old_param_map {
+                        if let Some((idx, _)) = table.get_column(&col) {
+                            if idx < old_params.len() {
+                                *e = Expr::Variable(format!(
+                                    "{}",
+                                    ctx.get_old_param(idx)
+                                        .expect("OLD parameters must be provided")
+                                        .get()
+                                ));
+                                return Ok(WalkControl::Continue);
+                            } else {
+                                crate::bail_parse_error!("no such column in OLD: {}", col);
+                            }
+                        }
+                        // Handle OLD.rowid
+                        if crate::translate::planner::ROWID_STRS
+                            .iter()
+                            .any(|s| s.eq_ignore_ascii_case(&col))
+                        {
+                            *e = Expr::Variable(format!(
+                                "{}",
+                                ctx.get_old_rowid_param()
+                                    .expect("OLD parameters must be provided")
+                            ));
+                            return Ok(WalkControl::Continue);
+                        }
+                        bail_parse_error!("no such column in OLD: {}", col);
+                    } else {
+                        bail_parse_error!(
+                            "OLD references are only valid in UPDATE and DELETE triggers"
+                        );
+                    }
+                }
+
+                // Handle unqualified column references - they refer to NEW if available, else OLD
+                if let Some((idx, _)) = table.get_column(&col) {
+                    if let Some(new_params) = &ctx.new_param_map {
+                        if idx < new_params.len() {
+                            *e = Expr::Variable(format!(
+                                "{}",
+                                ctx.get_new_param(idx)
+                                    .expect("NEW parameters must be provided")
+                                    .get()
+                            ));
+                            return Ok(WalkControl::Continue);
+                        }
+                    }
+                    if let Some(old_params) = &ctx.old_param_map {
+                        if idx < old_params.len() {
+                            *e = Expr::Variable(format!(
+                                "{}",
+                                ctx.get_old_param(idx)
+                                    .expect("OLD parameters must be provided")
+                                    .get()
+                            ));
+                            return Ok(WalkControl::Continue);
+                        }
+                    }
+                }
+
+                Ok(WalkControl::Continue)
+            }
+            _ => Ok(WalkControl::Continue),
+        }
+    })?;
+    Ok(())
+}
+
+/// Convert TriggerCmd to Stmt, rewriting NEW/OLD to Variable expressions (for subprogram compilation)
+fn trigger_cmd_to_stmt_for_subprogram(
+    cmd: &ast::TriggerCmd,
+    subprogram_ctx: &TriggerSubprogramContext,
+) -> Result<ast::Stmt> {
+    use turso_parser::ast::{InsertBody, QualifiedName};
+
+    match cmd {
+        ast::TriggerCmd::Insert {
+            or_conflict,
+            tbl_name,
+            col_names,
+            select,
+            upsert,
+            returning,
+        } => {
+            // Rewrite NEW/OLD references in the SELECT
+            let mut select_clone = select.clone();
+            rewrite_expressions_in_select_for_subprogram(&mut select_clone, subprogram_ctx)?;
+
+            let body = InsertBody::Select(select_clone, upsert.clone());
+            Ok(ast::Stmt::Insert {
+                with: None,
+                or_conflict: *or_conflict,
+                tbl_name: QualifiedName {
+                    db_name: None,
+                    name: tbl_name.clone(),
+                    alias: None,
+                },
+                columns: col_names.clone(),
+                body,
+                returning: returning.clone(),
+            })
+        }
+        ast::TriggerCmd::Update {
+            or_conflict,
+            tbl_name,
+            sets,
+            from,
+            where_clause,
+        } => {
+            // Rewrite NEW/OLD references in SET clauses and WHERE clause
+            let mut sets_clone = sets.clone();
+            for set in &mut sets_clone {
+                rewrite_trigger_expr_for_subprogram(
+                    &mut set.expr,
+                    &subprogram_ctx.table,
+                    subprogram_ctx,
+                )?;
+            }
+
+            let mut where_clause_clone = where_clause.clone();
+            if let Some(ref mut where_expr) = where_clause_clone {
+                rewrite_trigger_expr_for_subprogram(
+                    where_expr,
+                    &subprogram_ctx.table,
+                    subprogram_ctx,
+                )?;
+            }
+
+            Ok(ast::Stmt::Update(ast::Update {
+                with: None,
+                or_conflict: *or_conflict,
+                tbl_name: QualifiedName {
+                    db_name: None,
+                    name: tbl_name.clone(),
+                    alias: None,
+                },
+                indexed: None,
+                sets: sets_clone,
+                from: from.clone(),
+                where_clause: where_clause_clone,
+                returning: vec![],
+                order_by: vec![],
+                limit: None,
+            }))
+        }
+        ast::TriggerCmd::Delete {
+            tbl_name,
+            where_clause,
+        } => {
+            // Rewrite NEW/OLD references in WHERE clause
+            let mut where_clause_clone = where_clause.clone();
+            if let Some(ref mut where_expr) = where_clause_clone {
+                rewrite_trigger_expr_for_subprogram(
+                    where_expr,
+                    &subprogram_ctx.table,
+                    subprogram_ctx,
+                )?;
+            }
+
+            Ok(ast::Stmt::Delete {
+                tbl_name: QualifiedName {
+                    db_name: None,
+                    name: tbl_name.clone(),
+                    alias: None,
+                },
+                where_clause: where_clause_clone,
+                limit: None,
+                returning: vec![],
+                indexed: None,
+                order_by: vec![],
+                with: None,
+            })
+        }
+        ast::TriggerCmd::Select(select) => {
+            // Rewrite NEW/OLD references in the SELECT
+            let mut select_clone = select.clone();
+            rewrite_expressions_in_select_for_subprogram(&mut select_clone, subprogram_ctx)?;
+            Ok(ast::Stmt::Select(select_clone))
+        }
+    }
+}
+
+/// Rewrite NEW/OLD references in all expressions within a SELECT statement for subprogram
+fn rewrite_expressions_in_select_for_subprogram(
+    select: &mut ast::Select,
+    ctx: &TriggerSubprogramContext,
+) -> Result<()> {
+    use crate::translate::expr::walk_expr_mut;
+
+    // Rewrite expressions in the SELECT body
+    match &mut select.body.select {
+        ast::OneSelect::Select {
+            columns,
+            where_clause,
+            group_by,
+            ..
+        } => {
+            // Rewrite in columns
+            for col in columns {
+                if let ast::ResultColumn::Expr(ref mut expr, _) = col {
+                    walk_expr_mut(expr, &mut |e: &mut ast::Expr| {
+                        rewrite_trigger_expr_single_for_subprogram(e, ctx)?;
+                        Ok(crate::translate::expr::WalkControl::Continue)
+                    })?;
+                }
+            }
+
+            // Rewrite in WHERE clause
+            if let Some(ref mut where_expr) = where_clause {
+                walk_expr_mut(where_expr, &mut |e: &mut ast::Expr| {
+                    rewrite_trigger_expr_single_for_subprogram(e, ctx)?;
+                    Ok(crate::translate::expr::WalkControl::Continue)
+                })?;
+            }
+
+            // Rewrite in GROUP BY expressions and HAVING clause
+            if let Some(ref mut group_by) = group_by {
+                for expr in &mut group_by.exprs {
+                    walk_expr_mut(expr, &mut |e: &mut ast::Expr| {
+                        rewrite_trigger_expr_single_for_subprogram(e, ctx)?;
+                        Ok(crate::translate::expr::WalkControl::Continue)
+                    })?;
+                }
+
+                // Rewrite in HAVING clause
+                if let Some(ref mut having_expr) = group_by.having {
+                    walk_expr_mut(having_expr, &mut |e: &mut ast::Expr| {
+                        rewrite_trigger_expr_single_for_subprogram(e, ctx)?;
+                        Ok(crate::translate::expr::WalkControl::Continue)
+                    })?;
+                }
+            }
+        }
+        ast::OneSelect::Values(values) => {
+            for row in values {
+                for expr in row {
+                    walk_expr_mut(expr, &mut |e: &mut ast::Expr| {
+                        rewrite_trigger_expr_single_for_subprogram(e, ctx)?;
+                        Ok(crate::translate::expr::WalkControl::Continue)
+                    })?;
+                }
+            }
+        }
+    }
+
+    Ok(())
+}
+
+/// Rewrite a single NEW/OLD reference for subprogram (called from walk_expr_mut)
+fn rewrite_trigger_expr_single_for_subprogram(
+    e: &mut ast::Expr,
+    ctx: &TriggerSubprogramContext,
+) -> Result<()> {
+    match e {
+        Expr::Qualified(ns, col) | Expr::DoublyQualified(_, ns, col) => {
+            let ns = normalize_ident(ns.as_str());
+            let col = normalize_ident(col.as_str());
+
+            // Handle NEW.column references
+            if ns.eq_ignore_ascii_case("new") {
+                if let Some(new_params) = &ctx.new_param_map {
+                    if let Some((idx, col_def)) = ctx.table.get_column(&col) {
+                        if col_def.is_rowid_alias() {
+                            *e = Expr::Variable(format!(
+                                "{}",
+                                ctx.get_new_rowid_param()
+                                    .expect("NEW parameters must be provided")
+                            ));
+                            return Ok(());
+                        }
+                        if idx < new_params.len() {
+                            *e = Expr::Variable(format!(
+                                "{}",
+                                ctx.get_new_param(idx)
+                                    .expect("NEW parameters must be provided")
+                                    .get()
+                            ));
+                            return Ok(());
+                        } else {
+                            crate::bail_parse_error!("no such column in NEW: {}", col);
+                        }
+                    }
+                    // Handle NEW.rowid
+                    if crate::translate::planner::ROWID_STRS
+                        .iter()
+                        .any(|s| s.eq_ignore_ascii_case(&col))
+                    {
+                        *e = Expr::Variable(format!(
+                            "{}",
+                            ctx.get_new_rowid_param()
+                                .expect("NEW parameters must be provided")
+                        ));
+                        return Ok(());
+                    }
+                    bail_parse_error!("no such column in NEW: {}", col);
+                } else {
+                    bail_parse_error!(
+                        "NEW references are only valid in INSERT and UPDATE triggers"
+                    );
+                }
+            }
+
+            // Handle OLD.column references
+            if ns.eq_ignore_ascii_case("old") {
+                if let Some(old_params) = &ctx.old_param_map {
+                    if let Some((idx, col_def)) = ctx.table.get_column(&col) {
+                        if col_def.is_rowid_alias() {
+                            *e = Expr::Variable(format!(
+                                "{}",
+                                ctx.get_old_rowid_param()
+                                    .expect("OLD parameters must be provided")
+                            ));
+                            return Ok(());
+                        }
+                        if idx < old_params.len() {
+                            *e = Expr::Variable(format!(
+                                "{}",
+                                ctx.get_old_param(idx)
+                                    .expect("OLD parameters must be provided")
+                                    .get()
+                            ));
+                            return Ok(());
+                        } else {
+                            crate::bail_parse_error!("no such column in OLD: {}", col)
+                        }
+                    }
+                    // Handle OLD.rowid
+                    if crate::translate::planner::ROWID_STRS
+                        .iter()
+                        .any(|s| s.eq_ignore_ascii_case(&col))
+                    {
+                        *e = Expr::Variable(format!(
+                            "{}",
+                            ctx.get_old_rowid_param()
+                                .expect("OLD parameters must be provided")
+                        ));
+                        return Ok(());
+                    }
+                    bail_parse_error!("no such column in OLD: {}", col);
+                } else {
+                    bail_parse_error!(
+                        "OLD references are only valid in UPDATE and DELETE triggers"
+                    );
+                }
+            }
+
+            crate::bail_parse_error!("no such column: {ns}.{col}");
+        }
+        _ => {}
+    }
+    Ok(())
+}
+
+/// Execute trigger commands by compiling them as a subprogram and emitting Program instruction
+/// Returns true if there are triggers that will fire.
+fn execute_trigger_commands(
+    program: &mut ProgramBuilder,
+    resolver: &mut Resolver,
+    trigger: &Arc<Trigger>,
+    ctx: &TriggerContext,
+    connection: &Arc<crate::Connection>,
+) -> Result<bool> {
+    if connection.trigger_is_compiling(trigger) {
+        // Do not recursively compile the same trigger
+        return Ok(false);
+    }
+    connection.start_trigger_compilation(trigger.clone());
+    // Build parameter mapping: parameters are 1-indexed and sequential
+    // Order: [NEW values..., OLD values..., rowid]
+    // So if we have 2 NEW columns, 2 OLD columns: NEW params are 1,2; OLD params are 3,4; rowid is 5
+    let num_new = ctx.new_registers.as_ref().map(|r| r.len()).unwrap_or(0);
+
+    let new_param_map = ctx
+        .new_registers
+        .as_ref()
+        .map(|new_regs| {
+            (1..=new_regs.len())
+                .map(|i| NonZero::new(i).unwrap())
+                .collect()
+        })
+        .map(ParamMap);
+
+    let old_param_map = ctx
+        .old_registers
+        .as_ref()
+        .map(|old_regs| {
+            (1..=old_regs.len())
+                .map(|i| NonZero::new(i + num_new).unwrap())
+                .collect()
+        })
+        .map(ParamMap);
+
+    let subprogram_ctx = TriggerSubprogramContext {
+        new_param_map,
+        old_param_map,
+        table: ctx.table.clone(),
+    };
+    let mut subprogram_builder = ProgramBuilder::new_for_trigger(
+        QueryMode::Normal,
+        program.capture_data_changes_mode().clone(),
+        ProgramBuilderOpts {
+            num_cursors: 1,
+            approx_num_insns: 32,
+            approx_num_labels: 2,
+        },
+        trigger.clone(),
+    );
+    for command in trigger.commands.iter() {
+        let stmt = trigger_cmd_to_stmt_for_subprogram(command, &subprogram_ctx)?;
+        subprogram_builder.prologue();
+        subprogram_builder = translate_inner(
+            stmt,
+            resolver,
+            subprogram_builder,
+            connection,
+            "trigger subprogram",
+        )?;
+    }
+    subprogram_builder.epilogue(resolver.schema);
+    let built_subprogram = subprogram_builder.build(connection.clone(), true, "trigger subprogram");
+
+    let mut params = Vec::with_capacity(
+        ctx.new_registers.as_ref().map(|r| r.len()).unwrap_or(0)
+            + ctx.old_registers.as_ref().map(|r| r.len()).unwrap_or(0),
+    );
+    if let Some(new_regs) = &ctx.new_registers {
+        params.extend(
+            new_regs
+                .iter()
+                .copied()
+                .map(|reg_idx| crate::types::Value::Integer(reg_idx as i64)),
+        );
+    }
+    if let Some(old_regs) = &ctx.old_registers {
+        params.extend(
+            old_regs
+                .iter()
+                .copied()
+                .map(|reg_idx| crate::types::Value::Integer(reg_idx as i64)),
+        );
+    }
+
+    let turso_stmt = Statement::new(
+        built_subprogram,
+        connection.mv_store().cloned(),
+        connection.pager.load().clone(),
+        QueryMode::Normal,
+    );
+    program.emit_insn(Insn::Program {
+        params,
+        program: Arc::new(RwLock::new(turso_stmt)),
+    });
+    connection.end_trigger_compilation();
+
+    Ok(true)
+}
+
+/// Check if there are any triggers for a given event (regardless of time).
+/// This is used during plan preparation to determine if materialization is needed.
+pub fn has_relevant_triggers_type_only(
+    schema: &crate::schema::Schema,
+    event: TriggerEvent,
+    updated_column_indices: Option<&HashSet<usize>>,
+    table: &BTreeTable,
+) -> bool {
+    let mut triggers = schema.get_triggers_for_table(table.name.as_str());
+
+    // Filter triggers by event
+    triggers.any(|trigger| {
+        // Check event matches
+        let event_matches = match (&trigger.event, &event) {
+            (TriggerEvent::Delete, TriggerEvent::Delete) => true,
+            (TriggerEvent::Insert, TriggerEvent::Insert) => true,
+            (TriggerEvent::Update, TriggerEvent::Update) => true,
+            (TriggerEvent::UpdateOf(trigger_cols), TriggerEvent::Update) => {
+                // For UPDATE OF, we need to check if any of the specified columns
+                // are in the UPDATE SET clause
+                let updated_cols =
+                    updated_column_indices.expect("UPDATE should contain some updated columns");
+                // Check if any of the trigger's specified columns are being updated
+                trigger_cols.iter().any(|col_name| {
+                    let normalized_col = normalize_ident(col_name.as_str());
+                    if let Some((col_idx, _)) = table.get_column(&normalized_col) {
+                        updated_cols.contains(&col_idx)
+                    } else {
+                        // Column doesn't exist - according to SQLite docs, unrecognized
+                        // column names in UPDATE OF are silently ignored
+                        false
+                    }
+                })
+            }
+            _ => false,
+        };
+
+        event_matches
+    })
+}
+
+/// Check if there are any triggers for a given event (regardless of time).
+/// This is used during plan preparation to determine if materialization is needed.
+pub fn get_relevant_triggers_type_and_time<'a>(
+    schema: &'a crate::schema::Schema,
+    event: TriggerEvent,
+    time: TriggerTime,
+    updated_column_indices: Option<HashSet<usize>>,
+    table: &'a BTreeTable,
+) -> impl Iterator<Item = Arc<Trigger>> + 'a + Clone {
+    let triggers = schema.get_triggers_for_table(table.name.as_str());
+
+    // Filter triggers by event
+    triggers
+        .filter(move |trigger| -> bool {
+            // Check event matches
+            let event_matches = match (&trigger.event, &event) {
+                (TriggerEvent::Delete, TriggerEvent::Delete) => true,
+                (TriggerEvent::Insert, TriggerEvent::Insert) => true,
+                (TriggerEvent::Update, TriggerEvent::Update) => true,
+                (TriggerEvent::UpdateOf(trigger_cols), TriggerEvent::Update) => {
+                    // For UPDATE OF, we need to check if any of the specified columns
+                    // are in the UPDATE SET clause
+                    if let Some(ref updated_cols) = updated_column_indices {
+                        // Check if any of the trigger's specified columns are being updated
+                        trigger_cols.iter().any(|col_name| {
+                            let normalized_col = normalize_ident(col_name.as_str());
+                            if let Some((col_idx, _)) = table.get_column(&normalized_col) {
+                                updated_cols.contains(&col_idx)
+                            } else {
+                                // Column doesn't exist - according to SQLite docs, unrecognized
+                                // column names in UPDATE OF are silently ignored
+                                false
+                            }
+                        })
+                    } else {
+                        false
+                    }
+                }
+                _ => false,
+            };
+
+            if !event_matches {
+                return false;
+            }
+
+            trigger.time == time
+        })
+        .cloned()
+}
+
+pub fn fire_trigger(
+    program: &mut ProgramBuilder,
+    resolver: &mut Resolver,
+    trigger: Arc<Trigger>,
+    ctx: &TriggerContext,
+    connection: &Arc<crate::Connection>,
+) -> Result<()> {
+    // Evaluate WHEN clause if present
+    if let Some(mut when_expr) = trigger.when_clause.clone() {
+        // Rewrite NEW/OLD references in WHEN clause to use registers
+        rewrite_trigger_expr_for_when_clause(&mut when_expr, &ctx.table, ctx)?;
+
+        let when_reg = program.alloc_register();
+        translate_expr(program, None, &when_expr, when_reg, resolver)?;
+
+        let skip_label = program.allocate_label();
+        program.emit_insn(Insn::IfNot {
+            reg: when_reg,
+            jump_if_null: true,
+            target_pc: skip_label,
+        });
+
+        // Execute trigger commands if WHEN clause is true
+        execute_trigger_commands(program, resolver, &trigger, ctx, connection)?;
+
+        program.preassign_label_to_next_insn(skip_label);
+    } else {
+        // No WHEN clause - always execute
+        execute_trigger_commands(program, resolver, &trigger, ctx, connection)?;
+    }
+
+    Ok(())
+}
+
+/// Rewrite NEW/OLD references in WHEN clause expressions (uses Register expressions, not Variable)
+fn rewrite_trigger_expr_for_when_clause(
+    expr: &mut ast::Expr,
+    table: &BTreeTable,
+    ctx: &TriggerContext,
+) -> Result<()> {
+    use crate::translate::expr::walk_expr_mut;
+    use crate::translate::expr::WalkControl;
+
+    walk_expr_mut(expr, &mut |e: &mut ast::Expr| -> Result<WalkControl> {
+        match e {
+            Expr::Qualified(ns, col) | Expr::DoublyQualified(_, ns, col) => {
+                let ns = normalize_ident(ns.as_str());
+                let col = normalize_ident(col.as_str());
+
+                // Handle NEW.column references
+                if ns.eq_ignore_ascii_case("new") {
+                    if let Some(new_regs) = &ctx.new_registers {
+                        if let Some((idx, _)) = table.get_column(&col) {
+                            if idx < new_regs.len() {
+                                *e = Expr::Register(new_regs[idx]);
+                                return Ok(WalkControl::Continue);
+                            }
+                        }
+                        // Handle NEW.rowid
+                        if crate::translate::planner::ROWID_STRS
+                            .iter()
+                            .any(|s| s.eq_ignore_ascii_case(&col))
+                        {
+                            *e = Expr::Register(
+                                *ctx.new_registers
+                                    .as_ref()
+                                    .expect("NEW registers must be provided")
+                                    .last()
+                                    .expect("NEW registers must be provided"),
+                            );
+                            return Ok(WalkControl::Continue);
+                        }
+                        bail_parse_error!("no such column in NEW: {}", col);
+                    } else {
+                        bail_parse_error!(
+                            "NEW references are only valid in INSERT and UPDATE triggers"
+                        );
+                    }
+                }
+
+                // Handle OLD.column references
+                if ns.eq_ignore_ascii_case("old") {
+                    if let Some(old_regs) = &ctx.old_registers {
+                        if let Some((idx, _)) = table.get_column(&col) {
+                            if idx < old_regs.len() {
+                                *e = Expr::Register(old_regs[idx]);
+                                return Ok(WalkControl::Continue);
+                            }
+                        }
+                        // Handle OLD.rowid
+                        if crate::translate::planner::ROWID_STRS
+                            .iter()
+                            .any(|s| s.eq_ignore_ascii_case(&col))
+                        {
+                            *e = Expr::Register(
+                                *ctx.old_registers
+                                    .as_ref()
+                                    .expect("OLD registers must be provided")
+                                    .last()
+                                    .expect("OLD registers must be provided"),
+                            );
+                            return Ok(WalkControl::Continue);
+                        }
+                        bail_parse_error!("no such column in OLD: {}", col);
+                    } else {
+                        bail_parse_error!(
+                            "OLD references are only valid in UPDATE and DELETE triggers"
+                        );
+                    }
+                }
+
+                crate::bail_parse_error!("no such column: {ns}.{col}");
+            }
+            _ => Ok(WalkControl::Continue),
+        }
+    })?;
+    Ok(())
+}

core/translate/values.rs

@@ -34,6 +34,9 @@ pub fn emit_values(
         QueryDestination::RowValueSubqueryResult { .. } => {
             emit_toplevel_values(program, plan, t_ctx)?
         }
+        QueryDestination::RowSet { .. } => {
+            unreachable!("RowSet query destination should not be used in values emission")
+        }
         QueryDestination::Unset => unreachable!("Unset query destination should not be reached"),
     };
     Ok(reg_result_cols_start)
@@ -212,6 +215,9 @@ fn emit_values_to_destination(
                 extra_amount: num_regs - 1,
             });
         }
+        QueryDestination::RowSet { .. } => {
+            unreachable!("RowSet query destination should not be used in values emission")
+        }
         QueryDestination::Unset => unreachable!("Unset query destination should not be reached"),
     }
 }

core/vdbe/builder.rs

@@ -1,16 +1,17 @@
+use parking_lot::RwLock;
 use std::{
     cmp::Ordering,
     sync::{atomic::AtomicI64, Arc},
 };
 
 use tracing::{instrument, Level};
-use turso_parser::ast::{self, TableInternalId};
+use turso_parser::ast::{self, ResolveType, TableInternalId};
 
 use crate::{
     index_method::IndexMethodAttachment,
     numeric::Numeric,
     parameters::Parameters,
-    schema::{BTreeTable, Index, PseudoCursorType, Schema, Table},
+    schema::{BTreeTable, Index, PseudoCursorType, Schema, Table, Trigger},
     translate::{
         collate::CollationSeq,
         emitter::TransactionMode,
@@ -38,7 +39,7 @@ impl TableRefIdCounter {
     }
 }
 
-use super::{BranchOffset, CursorID, Insn, InsnReference, JumpTarget, Program};
+use super::{BranchOffset, CursorID, ExplainState, Insn, InsnReference, JumpTarget, Program};
 
 /// A key that uniquely identifies a cursor.
 /// The key is a pair of table reference id and index.
@@ -89,7 +90,7 @@ pub struct ProgramBuilder {
     next_free_register: usize,
     next_free_cursor_id: usize,
     /// Instruction, the function to execute it with, and its original index in the vector.
-    insns: Vec<(Insn, usize)>,
+    pub insns: Vec<(Insn, usize)>,
     /// A span of instructions from (offset_start_inclusive, offset_end_exclusive),
     /// that are deemed to be compile-time constant and can be hoisted out of loops
     /// so that they get evaluated only once at the start of the program.
@@ -127,6 +128,9 @@ pub struct ProgramBuilder {
     /// i.e. the individual statement may need to be aborted due to a constraint conflict, etc.
     /// instead of the entire transaction.
     needs_stmt_subtransactions: bool,
+    /// If this ProgramBuilder is building trigger subprogram, a ref to the trigger is stored here.
+    pub trigger: Option<Arc<Trigger>>,
+    pub resolve_type: ResolveType,
 }
 
 #[derive(Debug, Clone)]
@@ -189,6 +193,22 @@ impl ProgramBuilder {
         query_mode: QueryMode,
         capture_data_changes_mode: CaptureDataChangesMode,
         opts: ProgramBuilderOpts,
+    ) -> Self {
+        ProgramBuilder::_new(query_mode, capture_data_changes_mode, opts, None)
+    }
+    pub fn new_for_trigger(
+        query_mode: QueryMode,
+        capture_data_changes_mode: CaptureDataChangesMode,
+        opts: ProgramBuilderOpts,
+        trigger: Arc<Trigger>,
+    ) -> Self {
+        ProgramBuilder::_new(query_mode, capture_data_changes_mode, opts, Some(trigger))
+    }
+    fn _new(
+        query_mode: QueryMode,
+        capture_data_changes_mode: CaptureDataChangesMode,
+        opts: ProgramBuilderOpts,
+        trigger: Option<Arc<Trigger>>,
     ) -> Self {
         Self {
             table_reference_counter: TableRefIdCounter::new(),
@@ -215,9 +235,15 @@ impl ProgramBuilder {
             current_parent_explain_idx: None,
             reg_result_cols_start: None,
             needs_stmt_subtransactions: false,
+            trigger,
+            resolve_type: ResolveType::Abort,
         }
     }
 
+    pub fn set_resolve_type(&mut self, resolve_type: ResolveType) {
+        self.resolve_type = resolve_type;
+    }
+
     pub fn set_needs_stmt_subtransactions(&mut self, needs_stmt_subtransactions: bool) {
         self.needs_stmt_subtransactions = needs_stmt_subtransactions;
     }
@@ -829,6 +855,9 @@ impl ProgramBuilder {
                 Insn::VFilter { pc_if_empty, .. } => {
                     resolve(pc_if_empty, "VFilter");
                 }
+                Insn::RowSetRead { pc_if_empty, .. } => {
+                    resolve(pc_if_empty, "RowSetRead");
+                }
                 Insn::NoConflict { target_pc, .. } => {
                     resolve(target_pc, "NoConflict");
                 }
@@ -923,6 +952,15 @@ impl ProgramBuilder {
 
     /// Initialize the program with basic setup and return initial metadata and labels
     pub fn prologue(&mut self) {
+        if self.trigger.is_some() {
+            self.init_label = self.allocate_label();
+            self.emit_insn(Insn::Init {
+                target_pc: self.init_label,
+            });
+            self.preassign_label_to_next_insn(self.init_label);
+            self.start_offset = self.offset();
+            return;
+        }
         if self.nested_level == 0 {
             self.init_label = self.allocate_label();
 
@@ -961,6 +999,13 @@ impl ProgramBuilder {
     /// Note that although these are the final instructions, typically an SQLite
     /// query will jump to the Transaction instruction via init_label.
     pub fn epilogue(&mut self, schema: &Schema) {
+        if self.trigger.is_some() {
+            self.emit_insn(Insn::Halt {
+                err_code: 0,
+                description: "trigger".to_string(),
+            });
+            return;
+        }
         if self.nested_level == 0 {
             // "rollback" flag is used to determine if halt should rollback the transaction.
             self.emit_halt(self.rollback);
@@ -1110,6 +1155,9 @@ impl ProgramBuilder {
             sql: sql.to_string(),
             accesses_db: !matches!(self.txn_mode, TransactionMode::None),
             needs_stmt_subtransactions: self.needs_stmt_subtransactions,
+            trigger: self.trigger.take(),
+            resolve_type: self.resolve_type,
+            explain_state: RwLock::new(ExplainState::default()),
         }
     }
 }

core/vdbe/execute.rs

@@ -23,7 +23,7 @@ use crate::util::{
 use crate::vdbe::affinity::{apply_numeric_affinity, try_for_float, Affinity, ParsedNumber};
 use crate::vdbe::insn::InsertFlags;
 use crate::vdbe::value::ComparisonOp;
-use crate::vdbe::{registers_to_ref_values, EndStatement, TxnCleanup};
+use crate::vdbe::{registers_to_ref_values, EndStatement, StepResult, TxnCleanup};
 use crate::vector::{vector32_sparse, vector_concat, vector_distance_jaccard, vector_slice};
 use crate::{
     error::{
@@ -39,13 +39,14 @@ use crate::{
     },
     translate::emitter::TransactionMode,
 };
-use crate::{get_cursor, CheckpointMode, Connection, DatabaseStorage, MvCursor};
+use crate::{get_cursor, CheckpointMode, Completion, Connection, DatabaseStorage, MvCursor};
 use either::Either;
 use std::any::Any;
 use std::env::temp_dir;
 use std::ops::DerefMut;
 use std::{
     borrow::BorrowMut,
+    num::NonZero,
     sync::{atomic::Ordering, Arc, Mutex},
 };
 use turso_macros::match_ignore_ascii_case;
@@ -75,7 +76,7 @@ use super::{
     CommitState,
 };
 use parking_lot::RwLock;
-use turso_parser::ast::{self, ForeignKeyClause, Name};
+use turso_parser::ast::{self, ForeignKeyClause, Name, ResolveType};
 use turso_parser::parser::Parser;
 
 use super::{
@@ -2068,8 +2069,6 @@ pub fn halt(
     description: &str,
 ) -> Result<InsnFunctionStepResult> {
     if err_code > 0 {
-        // Any non-FK constraint violation causes the statement subtransaction to roll back.
-        state.end_statement(&program.connection, pager, EndStatement::RollbackSavepoint)?;
         vtab_rollback_all(&program.connection, state)?;
     }
     match err_code {
@@ -2107,12 +2106,15 @@ pub fn halt(
             .load(Ordering::Acquire)
             > 0
     {
-        state.end_statement(&program.connection, pager, EndStatement::RollbackSavepoint)?;
         return Err(LimboError::Constraint(
             "foreign key constraint failed".to_string(),
         ));
     }
 
+    if program.is_trigger_subprogram() {
+        return Ok(InsnFunctionStepResult::Done);
+    }
+
     if auto_commit {
         // In autocommit mode, a statement that leaves deferred violations must fail here,
         // and it also ends the transaction.
@@ -2256,6 +2258,11 @@ pub fn op_transaction_inner(
         },
         insn
     );
+    if program.is_trigger_subprogram() {
+        crate::bail_parse_error!(
+            "Transaction instruction should not be used in trigger subprograms"
+        );
+    }
     let pager = program.get_pager_from_database_index(db);
     loop {
         match state.op_transaction_state {
@@ -2537,6 +2544,12 @@ pub fn op_auto_commit(
         }
     }
 
+    if program.is_trigger_subprogram() {
+        // Trigger subprograms never commit or rollback.
+        state.pc += 1;
+        return Ok(InsnFunctionStepResult::Step);
+    }
+
     let res = program
         .commit_txn(pager.clone(), state, mv_store, requested_rollback)
         .map(Into::into);
@@ -2643,6 +2656,100 @@ pub fn op_integer(
     Ok(InsnFunctionStepResult::Step)
 }
 
+pub enum OpProgramState {
+    Start,
+    Step,
+}
+
+/// Execute a trigger subprogram (Program opcode).
+pub fn op_program(
+    program: &Program,
+    state: &mut ProgramState,
+    insn: &Insn,
+    pager: &Arc<Pager>,
+    mv_store: Option<&Arc<MvStore>>,
+) -> Result<InsnFunctionStepResult> {
+    load_insn!(
+        Program {
+            params,
+            program: subprogram,
+        },
+        insn
+    );
+    loop {
+        match &mut state.op_program_state {
+            OpProgramState::Start => {
+                let mut statement = subprogram.write();
+                statement.reset();
+                let Some(ref trigger) = statement.get_trigger() else {
+                    crate::bail_parse_error!("trigger subprogram has no trigger");
+                };
+                program.connection.start_trigger_execution(trigger.clone());
+
+                // Extract register values from params (which contain register indices encoded as negative integers)
+                // and bind them to the subprogram's parameters
+                for (param_idx, param_value) in params.iter().enumerate() {
+                    if let Value::Integer(reg_idx) = param_value {
+                        let reg_idx = *reg_idx as usize;
+                        if reg_idx < state.registers.len() {
+                            let value = state.registers[reg_idx].get_value().clone();
+                            let param_index = NonZero::<usize>::new(param_idx + 1).unwrap();
+                            statement.bind_at(param_index, value);
+                        } else {
+                            crate::bail_corrupt_error!(
+                                "Register index {} out of bounds (len={})",
+                                reg_idx,
+                                state.registers.len()
+                            );
+                        }
+                    } else {
+                        crate::bail_parse_error!(
+                            "Trigger parameters should be integers, got {:?}",
+                            param_value
+                        );
+                    }
+                }
+
+                state.op_program_state = OpProgramState::Step;
+            }
+            OpProgramState::Step => {
+                loop {
+                    let mut statement = subprogram.write();
+                    let res = statement.step();
+                    match res {
+                        Ok(step_result) => match step_result {
+                            StepResult::Done => break,
+                            StepResult::IO => {
+                                return Ok(InsnFunctionStepResult::IO(IOCompletions::Single(
+                                    Completion::new_yield(),
+                                )));
+                            }
+                            StepResult::Row => continue,
+                            StepResult::Interrupt | StepResult::Busy => {
+                                return Err(LimboError::Busy);
+                            }
+                        },
+                        Err(LimboError::Constraint(constraint_err)) => {
+                            if program.resolve_type != ResolveType::Ignore {
+                                return Err(LimboError::Constraint(constraint_err));
+                            }
+                            break;
+                        }
+                        Err(err) => {
+                            return Err(err);
+                        }
+                    }
+                }
+                program.connection.end_trigger_execution();
+
+                state.op_program_state = OpProgramState::Start;
+                state.pc += 1;
+                return Ok(InsnFunctionStepResult::Step);
+            }
+        }
+    }
+}
+
 pub fn op_real(
     program: &Program,
     state: &mut ProgramState,
@@ -6570,7 +6677,6 @@ pub fn op_idx_delete(
         insn
     );
 
-    tracing::info!("idx_delete cursor: {:?}", program.cursor_ref[*cursor_id]);
     if let Some(Cursor::IndexMethod(cursor)) = &mut state.cursors[*cursor_id] {
         return_if_io!(cursor.delete(&state.registers[*start_reg..*start_reg + *num_regs]));
         state.pc += 1;
@@ -7596,6 +7702,24 @@ pub fn op_drop_view(
     Ok(InsnFunctionStepResult::Step)
 }
 
+pub fn op_drop_trigger(
+    program: &Program,
+    state: &mut ProgramState,
+    insn: &Insn,
+    pager: &Arc<Pager>,
+    mv_store: Option<&Arc<MvStore>>,
+) -> Result<InsnFunctionStepResult> {
+    load_insn!(DropTrigger { db, trigger_name }, insn);
+
+    let conn = program.connection.clone();
+    conn.with_schema_mut(|schema| {
+        schema.remove_trigger(trigger_name)?;
+        Ok::<(), crate::LimboError>(())
+    })?;
+    state.pc += 1;
+    Ok(InsnFunctionStepResult::Step)
+}
+
 pub fn op_close(
     program: &Program,
     state: &mut ProgramState,
@@ -7606,6 +7730,9 @@ pub fn op_close(
     load_insn!(Close { cursor_id }, insn);
     let cursors = &mut state.cursors;
     cursors.get_mut(*cursor_id).unwrap().take();
+    if let Some(deferred_seek) = state.deferred_seeks.get_mut(*cursor_id) {
+        deferred_seek.take();
+    }
     state.pc += 1;
     Ok(InsnFunctionStepResult::Step)
 }

core/vdbe/explain.rs

@@ -727,6 +727,23 @@ pub fn insn_to_row(
                 0,
                 format!("r[{dest}]={value}"),
             ),
+            Insn::Program {
+                params,
+                ..
+            } => (
+                "Program",
+                // First register that contains a param
+                params.first().map(|v| match v {
+                    crate::types::Value::Integer(i) if *i < 0 => (-i - 1) as i32,
+                    _ => 0,
+                }).unwrap_or(0),
+                // Number of registers that contain params
+                params.len() as i32,
+                0,
+                Value::build_text(program.sql.clone()),
+                0,
+                format!("subprogram={}", program.sql),
+            ),
             Insn::Real { value, dest } => (
                 "Real",
                 0,
@@ -1407,6 +1424,15 @@ pub fn insn_to_row(
                 0,
                 format!("DROP TABLE {table_name}"),
             ),
+            Insn::DropTrigger { db, trigger_name } => (
+                "DropTrigger",
+                *db as i32,
+                0,
+                0,
+                Value::build_text(trigger_name.clone()),
+                0,
+                format!("DROP TRIGGER {trigger_name}"),
+            ),
             Insn::DropView { db, view_name } => (
                 "DropView",
                 *db as i32,

core/vdbe/insn.rs

@@ -10,8 +10,9 @@ use crate::{
     translate::{collate::CollationSeq, emitter::TransactionMode},
     types::KeyInfo,
     vdbe::affinity::Affinity,
-    Value,
+    Statement, Value,
 };
+use parking_lot::RwLock;
 use strum::EnumCount;
 use strum_macros::{EnumDiscriminants, FromRepr, VariantArray};
 use turso_macros::Description;
@@ -530,6 +531,18 @@ pub enum Insn {
         can_fallthrough: bool,
     },
 
+    /// Invoke a trigger subprogram.
+    ///
+    /// According to SQLite documentation (https://sqlite.org/opcode.html):
+    /// "The Program opcode invokes the trigger subprogram. The Program instruction
+    /// allocates and initializes a fresh register set for each invocation of the
+    /// subprogram, so subprograms can be reentrant and recursive. The Param opcode
+    /// is used by subprograms to access content in registers of the calling bytecode program."
+    Program {
+        params: Vec<Value>,
+        program: Arc<RwLock<Statement>>,
+    },
+
     /// Write an integer value into a register.
     Integer {
         value: i64,
@@ -980,6 +993,13 @@ pub enum Insn {
         //  The name of the index being dropped
         index: Arc<Index>,
     },
+    /// Drop a trigger
+    DropTrigger {
+        /// The database within which this trigger needs to be dropped (P1).
+        db: usize,
+        /// The name of the trigger being dropped
+        trigger_name: String,
+    },
 
     /// Close a cursor.
     Close {
@@ -1329,6 +1349,7 @@ impl InsnVariants {
             InsnVariants::Gosub => execute::op_gosub,
             InsnVariants::Return => execute::op_return,
             InsnVariants::Integer => execute::op_integer,
+            InsnVariants::Program => execute::op_program,
             InsnVariants::Real => execute::op_real,
             InsnVariants::RealAffinity => execute::op_real_affinity,
             InsnVariants::String8 => execute::op_string8,
@@ -1383,6 +1404,7 @@ impl InsnVariants {
             InsnVariants::Destroy => execute::op_destroy,
             InsnVariants::ResetSorter => execute::op_reset_sorter,
             InsnVariants::DropTable => execute::op_drop_table,
+            InsnVariants::DropTrigger => execute::op_drop_trigger,
             InsnVariants::DropView => execute::op_drop_view,
             InsnVariants::Close => execute::op_close,
             InsnVariants::IsNull => execute::op_is_null,

core/vdbe/mod.rs

@@ -33,6 +33,7 @@ use crate::{
     function::{AggFunc, FuncCtx},
     mvcc::{database::CommitStateMachine, LocalClock},
     return_if_io,
+    schema::Trigger,
     state_machine::StateMachine,
     storage::{pager::PagerCommitResult, sqlite3_ondisk::SmallVec},
     translate::{collate::CollationSeq, plan::TableReferences},
@@ -41,7 +42,7 @@ use crate::{
         execute::{
             OpCheckpointState, OpColumnState, OpDeleteState, OpDeleteSubState, OpDestroyState,
             OpIdxInsertState, OpInsertState, OpInsertSubState, OpNewRowidState, OpNoConflictState,
-            OpRowIdState, OpSeekState, OpTransactionState,
+            OpProgramState, OpRowIdState, OpSeekState, OpTransactionState,
         },
         metrics::StatementMetrics,
     },
@@ -63,6 +64,8 @@ use execute::{
     InsnFunction, InsnFunctionStepResult, OpIdxDeleteState, OpIntegrityCheckState,
     OpOpenEphemeralState,
 };
+use parking_lot::RwLock;
+use turso_parser::ast::ResolveType;
 
 use crate::vdbe::rowset::RowSet;
 use explain::{insn_to_row_with_comment, EXPLAIN_COLUMNS, EXPLAIN_QUERY_PLAN_COLUMNS};
@@ -296,6 +299,7 @@ pub struct ProgramState {
     /// Metrics collected during statement execution
     pub metrics: StatementMetrics,
     op_open_ephemeral_state: OpOpenEphemeralState,
+    op_program_state: OpProgramState,
     op_new_rowid_state: OpNewRowidState,
     op_idx_insert_state: OpIdxInsertState,
     op_insert_state: OpInsertState,
@@ -324,6 +328,12 @@ pub struct ProgramState {
     rowsets: HashMap<usize, RowSet>,
 }
 
+impl std::fmt::Debug for Program {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Program").finish()
+    }
+}
+
 // SAFETY: This needs to be audited for thread safety.
 // See: https://github.com/tursodatabase/turso/issues/1552
 unsafe impl Send for ProgramState {}
@@ -360,6 +370,7 @@ impl ProgramState {
             op_integrity_check_state: OpIntegrityCheckState::Start,
             metrics: StatementMetrics::new(),
             op_open_ephemeral_state: OpOpenEphemeralState::Start,
+            op_program_state: OpProgramState::Start,
             op_new_rowid_state: OpNewRowidState::Start,
             op_idx_insert_state: OpIdxInsertState::MaybeSeek,
             op_insert_state: OpInsertState {
@@ -515,7 +526,12 @@ impl ProgramState {
         match end_statement {
             EndStatement::ReleaseSavepoint => pager.release_savepoint(),
             EndStatement::RollbackSavepoint => {
-                pager.rollback_to_newest_savepoint()?;
+                let stmt_was_rolled_back = pager.rollback_to_newest_savepoint()?;
+                if !stmt_was_rolled_back {
+                    // We sometimes call end_statement() on errors without explicitly knowing whether a stmt transaction
+                    // caused the error or not. If it didn't, don't reset any FK violation counters.
+                    return Ok(());
+                }
                 // Reset the deferred foreign key violations counter to the value it had at the start of the statement.
                 // This is used to ensure that if an interactive transaction had deferred FK violations, they are not lost.
                 connection.fk_deferred_violations.store(
@@ -583,6 +599,17 @@ macro_rules! get_cursor {
     };
 }
 
+/// Tracks the state of explain mode execution, including which subprograms need to be processed.
+#[derive(Default)]
+pub struct ExplainState {
+    /// Program counter positions in the parent program where `Insn::Program` instructions occur.
+    parent_program_pcs: Vec<usize>,
+    /// Index of the subprogram currently being processed, if any.
+    current_subprogram_index: Option<usize>,
+    /// PC value when we started processing the current subprogram, to detect if we need to reset.
+    subprogram_start_pc: Option<usize>,
+}
+
 pub struct Program {
     pub max_registers: usize,
     // we store original indices because we don't want to create new vec from
@@ -605,6 +632,9 @@ pub struct Program {
     /// is determined by the parser flags "mayAbort" and "isMultiWrite". Essentially this means that the individual
     /// statement may need to be aborted due to a constraint conflict, etc. instead of the entire transaction.
     pub needs_stmt_subtransactions: bool,
+    pub trigger: Option<Arc<Trigger>>,
+    pub resolve_type: ResolveType,
+    pub explain_state: RwLock<ExplainState>,
 }
 
 impl Program {
@@ -650,11 +680,106 @@ impl Program {
         // FIXME: do we need this?
         state.metrics.vm_steps = state.metrics.vm_steps.saturating_add(1);
 
-        if state.pc as usize >= self.insns.len() {
+        let mut explain_state = self.explain_state.write();
+
+        // Check if we're processing a subprogram
+        if let Some(sub_idx) = explain_state.current_subprogram_index {
+            if sub_idx >= explain_state.parent_program_pcs.len() {
+                // All subprograms processed
+                *explain_state = ExplainState::default();
                 return Ok(StepResult::Done);
             }
 
+            let parent_pc = explain_state.parent_program_pcs[sub_idx];
+            let Insn::Program { program: p, .. } = &self.insns[parent_pc].0 else {
+                panic!("Expected program insn at pc {parent_pc}");
+            };
+            let p = &mut p.write().program;
+
+            let subprogram_insn_count = p.insns.len();
+
+            // Check if the subprogram has already finished (PC is out of bounds)
+            // This can happen if the subprogram finished in a previous call but we're being called again
+            if state.pc as usize >= subprogram_insn_count {
+                // Subprogram is done, move to next one
+                explain_state.subprogram_start_pc = None;
+                if sub_idx + 1 < explain_state.parent_program_pcs.len() {
+                    explain_state.current_subprogram_index = Some(sub_idx + 1);
+                    state.pc = 0;
+                    drop(explain_state);
+                    return self.explain_step(state, _mv_store, pager);
+                } else {
+                    *explain_state = ExplainState::default();
+                    return Ok(StepResult::Done);
+                }
+            }
+
+            // Reset PC to 0 only when starting a new subprogram (when subprogram_start_pc is None)
+            // Once we've started, let the subprogram manage its own PC through its explain_step
+            if explain_state.subprogram_start_pc.is_none() {
+                state.pc = 0;
+                explain_state.subprogram_start_pc = Some(0);
+            }
+
+            // Process the subprogram - it will handle its own explain_step internally
+            // The subprogram's explain_step will process all its instructions (including any nested subprograms)
+            // and return StepResult::Row for each instruction, then StepResult::Done when finished
+            let result = p.step(state, None, pager.clone(), QueryMode::Explain, None)?;
+
+            match result {
+                StepResult::Done => {
+                    // This subprogram is done, move to next one
+                    explain_state.subprogram_start_pc = None; // Clear the start PC marker
+                    if sub_idx + 1 < explain_state.parent_program_pcs.len() {
+                        // Move to next subprogram
+                        explain_state.current_subprogram_index = Some(sub_idx + 1);
+                        // Reset PC to 0 for the next subprogram
+                        state.pc = 0;
+                        // Recursively call to process the next subprogram
+                        drop(explain_state);
+                        return self.explain_step(state, _mv_store, pager);
+                    } else {
+                        // All subprograms done
+                        *explain_state = ExplainState::default();
+                        return Ok(StepResult::Done);
+                    }
+                }
+                StepResult::Row => {
+                    // Output a row from the subprogram
+                    // The subprogram's step already set up the registers with PC starting at 0
+                    // Don't reset subprogram_start_pc - we're still processing this subprogram
+                    drop(explain_state);
+                    return Ok(StepResult::Row);
+                }
+                other => {
+                    drop(explain_state);
+                    return Ok(other);
+                }
+            }
+        }
+
+        // We're processing the parent program
+        if state.pc as usize >= self.insns.len() {
+            // Parent program is done, start processing subprograms
+            if explain_state.parent_program_pcs.is_empty() {
+                // No subprograms to process
+                *explain_state = ExplainState::default();
+                return Ok(StepResult::Done);
+            }
+
+            // Start processing the first subprogram
+            explain_state.current_subprogram_index = Some(0);
+            explain_state.subprogram_start_pc = None; // Will be set when we actually start processing
+            state.pc = 0; // Reset PC to 0 for the first subprogram
+            drop(explain_state);
+            return self.explain_step(state, _mv_store, pager);
+        }
+
         let (current_insn, _) = &self.insns[state.pc as usize];
+
+        if matches!(current_insn, Insn::Program { .. }) {
+            explain_state.parent_program_pcs.push(state.pc as usize);
+        }
         let (opcode, p1, p2, p3, p4, p5, comment) = insn_to_row_with_comment(
             self,
             current_insn,
@@ -747,7 +872,7 @@ impl Program {
                 return Err(LimboError::InternalError("Connection closed".to_string()));
             }
             if state.is_interrupted() {
-                self.abort(mv_store, &pager, None, &mut state.auto_txn_cleanup);
+                self.abort(mv_store, &pager, None, state);
                 return Ok(StepResult::Interrupt);
             }
             if let Some(io) = &state.io_completions {
@@ -757,7 +882,7 @@ impl Program {
                 }
                 if let Some(err) = io.get_error() {
                     let err = err.into();
-                    self.abort(mv_store, &pager, Some(&err), &mut state.auto_txn_cleanup);
+                    self.abort(mv_store, &pager, Some(&err), state);
                     return Err(err);
                 }
                 state.io_completions = None;
@@ -799,7 +924,7 @@ impl Program {
                     return Ok(StepResult::Busy);
                 }
                 Err(err) => {
-                    self.abort(mv_store, &pager, Some(&err), &mut state.auto_txn_cleanup);
+                    self.abort(mv_store, &pager, Some(&err), state);
                     return Err(err);
                 }
             }
@@ -1059,10 +1184,21 @@ impl Program {
         mv_store: Option<&Arc<MvStore>>,
         pager: &Arc<Pager>,
         err: Option<&LimboError>,
-        cleanup: &mut TxnCleanup,
+        state: &mut ProgramState,
     ) {
+        if self.is_trigger_subprogram() {
+            self.connection.end_trigger_execution();
+        }
         // Errors from nested statements are handled by the parent statement.
-        if !self.connection.is_nested_stmt() {
+        if !self.connection.is_nested_stmt() && !self.is_trigger_subprogram() {
+            if err.is_some() {
+                // Any error apart from deferred FK volations causes the statement subtransaction to roll back.
+                let res =
+                    state.end_statement(&self.connection, pager, EndStatement::RollbackSavepoint);
+                if let Err(e) = res {
+                    tracing::error!("Error rolling back statement: {}", e);
+                }
+            }
             match err {
                 // Transaction errors, e.g. trying to start a nested transaction, do not cause a rollback.
                 Some(LimboError::TxError(_)) => {}
@@ -1075,7 +1211,7 @@ impl Program {
                 // and op_halt.
                 Some(LimboError::Constraint(_)) => {}
                 _ => {
-                    if *cleanup != TxnCleanup::None || err.is_some() {
+                    if state.auto_txn_cleanup != TxnCleanup::None || err.is_some() {
                         if let Some(mv_store) = mv_store {
                             if let Some(tx_id) = self.connection.get_mv_tx_id() {
                                 self.connection.auto_commit.store(true, Ordering::SeqCst);
@@ -1090,7 +1226,11 @@ impl Program {
                 }
             }
         }
-        *cleanup = TxnCleanup::None;
+        state.auto_txn_cleanup = TxnCleanup::None;
+    }
+
+    pub fn is_trigger_subprogram(&self) -> bool {
+        self.trigger.is_some()
     }
 }
 

testing/trigger.test

@@ -0,0 +1,761 @@
+#!/usr/bin/env tclsh
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+
+# Basic CREATE TRIGGER
+do_execsql_test_on_specific_db {:memory:} trigger-create-basic {
+  CREATE TABLE test1 (x INTEGER, y TEXT);
+  CREATE TRIGGER t1 BEFORE INSERT ON test1 BEGIN INSERT INTO test1 VALUES (100, 'triggered'); END;
+  INSERT INTO test1 VALUES (1, 'hello');
+  SELECT * FROM test1 ORDER BY rowid;
+} {100|triggered
+1|hello}
+
+# CREATE TRIGGER IF NOT EXISTS
+do_execsql_test_on_specific_db {:memory:} trigger-create-if-not-exists {
+  CREATE TABLE test2 (x INTEGER PRIMARY KEY);
+  CREATE TRIGGER IF NOT EXISTS t2 BEFORE INSERT ON test2 BEGIN SELECT 1; END;
+  CREATE TRIGGER IF NOT EXISTS t2 BEFORE INSERT ON test2 BEGIN SELECT 1; END;
+  SELECT name FROM sqlite_schema WHERE type='trigger' AND name='t2';
+} {t2}
+
+# DROP TRIGGER
+do_execsql_test_on_specific_db {:memory:} trigger-drop-basic {
+  CREATE TABLE test3 (x INTEGER PRIMARY KEY);
+  CREATE TRIGGER t3 BEFORE INSERT ON test3 BEGIN SELECT 1; END;
+  DROP TRIGGER t3;
+  SELECT name FROM sqlite_schema WHERE type='trigger' AND name='t3';
+} {}
+
+# DROP TRIGGER IF EXISTS
+do_execsql_test_on_specific_db {:memory:} trigger-drop-if-exists {
+  CREATE TABLE test4 (x INTEGER PRIMARY KEY);
+  DROP TRIGGER IF EXISTS nonexistent;
+  CREATE TRIGGER t4 BEFORE INSERT ON test4 BEGIN SELECT 1; END;
+  DROP TRIGGER IF EXISTS t4;
+  SELECT name FROM sqlite_schema WHERE type='trigger' AND name='t4';
+} {}
+
+# BEFORE INSERT trigger
+do_execsql_test_on_specific_db {:memory:} trigger-before-insert {
+  CREATE TABLE test5 (x INTEGER PRIMARY KEY, y TEXT);
+  CREATE TRIGGER t5 BEFORE INSERT ON test5 BEGIN UPDATE test5 SET y = 'before_' || y WHERE x = NEW.x; END;
+  INSERT INTO test5 VALUES (1, 'hello');
+  SELECT * FROM test5;
+} {1|hello}
+
+# AFTER INSERT trigger
+do_execsql_test_on_specific_db {:memory:} trigger-after-insert {
+  CREATE TABLE test6 (x INTEGER PRIMARY KEY, y TEXT);
+  CREATE TABLE log6 (x INTEGER, y TEXT);
+  CREATE TRIGGER t6 AFTER INSERT ON test6 BEGIN INSERT INTO log6 VALUES (NEW.x, NEW.y); END;
+  INSERT INTO test6 VALUES (1, 'hello');
+  SELECT * FROM log6;
+} {1|hello}
+
+# BEFORE UPDATE trigger
+do_execsql_test_on_specific_db {:memory:} trigger-before-update {
+  CREATE TABLE test7 (x INTEGER PRIMARY KEY, y TEXT);
+  INSERT INTO test7 VALUES (1, 'hello');
+  CREATE TRIGGER t7 BEFORE UPDATE ON test7 BEGIN UPDATE test7 SET y = 'before_' || NEW.y WHERE x = OLD.x; END;
+  UPDATE test7 SET y = 'world' WHERE x = 1;
+  SELECT * FROM test7;
+} {1|world}
+
+# AFTER UPDATE trigger
+do_execsql_test_on_specific_db {:memory:} trigger-after-update {
+  CREATE TABLE test8 (x INTEGER PRIMARY KEY, y TEXT);
+  CREATE TABLE log8 (old_x INTEGER, old_y TEXT, new_x INTEGER, new_y TEXT);
+  INSERT INTO test8 VALUES (1, 'hello');
+  CREATE TRIGGER t8 AFTER UPDATE ON test8 BEGIN INSERT INTO log8 VALUES (OLD.x, OLD.y, NEW.x, NEW.y); END;
+  UPDATE test8 SET y = 'world' WHERE x = 1;
+  SELECT * FROM log8;
+} {1|hello|1|world}
+
+# BEFORE DELETE trigger
+do_execsql_test_on_specific_db {:memory:} trigger-before-delete {
+  CREATE TABLE test9 (x INTEGER PRIMARY KEY, y TEXT);
+  CREATE TABLE log9 (x INTEGER, y TEXT);
+  INSERT INTO test9 VALUES (1, 'hello');
+  CREATE TRIGGER t9 BEFORE DELETE ON test9 BEGIN INSERT INTO log9 VALUES (OLD.x, OLD.y); END;
+  DELETE FROM test9 WHERE x = 1;
+  SELECT * FROM log9;
+} {1|hello}
+
+# AFTER DELETE trigger
+do_execsql_test_on_specific_db {:memory:} trigger-after-delete {
+  CREATE TABLE test10 (x INTEGER PRIMARY KEY, y TEXT);
+  CREATE TABLE log10 (x INTEGER, y TEXT);
+  INSERT INTO test10 VALUES (1, 'hello');
+  CREATE TRIGGER t10 AFTER DELETE ON test10 BEGIN INSERT INTO log10 VALUES (OLD.x, OLD.y); END;
+  DELETE FROM test10 WHERE x = 1;
+  SELECT * FROM log10;
+} {1|hello}
+
+# Trigger with WHEN clause
+do_execsql_test_on_specific_db {:memory:} trigger-when-clause {
+  CREATE TABLE test11 (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log11 (x INTEGER);
+  CREATE TRIGGER t11 AFTER INSERT ON test11 WHEN NEW.y > 10 BEGIN INSERT INTO log11 VALUES (NEW.x); END;
+  INSERT INTO test11 VALUES (1, 5);
+  INSERT INTO test11 VALUES (2, 15);
+  SELECT * FROM log11;
+} {2}
+
+# Multiple triggers on same event
+do_execsql_test_on_specific_db {:memory:} trigger-multiple-same-event {
+  CREATE TABLE test12 (x INTEGER PRIMARY KEY);
+  CREATE TABLE log12 (msg TEXT);
+  CREATE TRIGGER t12a BEFORE INSERT ON test12 BEGIN INSERT INTO log12 VALUES ('trigger1'); END;
+  CREATE TRIGGER t12b BEFORE INSERT ON test12 BEGIN INSERT INTO log12 VALUES ('trigger2'); END;
+  INSERT INTO test12 VALUES (1);
+  SELECT * FROM log12 ORDER BY msg;
+} {trigger1
+trigger2}
+
+# Triggers dropped when table is dropped
+do_execsql_test_on_specific_db {:memory:} trigger-drop-table-drops-triggers {
+  CREATE TABLE test13 (x INTEGER PRIMARY KEY);
+  CREATE TRIGGER t13 BEFORE INSERT ON test13 BEGIN SELECT 1; END;
+  DROP TABLE test13;
+  SELECT name FROM sqlite_schema WHERE type='trigger' AND name='t13';
+} {}
+
+# NEW and OLD references
+do_execsql_test_on_specific_db {:memory:} trigger-new-old-references {
+  CREATE TABLE test14 (x INTEGER PRIMARY KEY, y TEXT);
+  CREATE TABLE log14 (msg TEXT);
+  INSERT INTO test14 VALUES (1, 'hello');
+  CREATE TRIGGER t14 AFTER UPDATE ON test14 BEGIN INSERT INTO log14 VALUES ('old=' || OLD.y || ' new=' || NEW.y); END;
+  UPDATE test14 SET y = 'world' WHERE x = 1;
+  SELECT * FROM log14;
+} {"old=hello new=world"}
+
+# Trigger with UPDATE OF clause
+do_execsql_test_on_specific_db {:memory:} trigger-update-of {
+  CREATE TABLE test15 (x INTEGER PRIMARY KEY, y TEXT, z TEXT);
+  CREATE TABLE log15 (msg TEXT);
+  INSERT INTO test15 VALUES (1, 'hello', 'world');
+  CREATE TRIGGER t15 AFTER UPDATE OF y ON test15 BEGIN INSERT INTO log15 VALUES ('y changed'); END;
+  UPDATE test15 SET z = 'foo' WHERE x = 1;
+  SELECT * FROM log15;
+  UPDATE test15 SET y = 'bar' WHERE x = 1;
+  SELECT * FROM log15;
+} {"y changed"}
+
+# Recursive trigger - AFTER INSERT inserting into same table
+do_execsql_test_on_specific_db {:memory:} trigger-recursive-after-insert {
+  CREATE TABLE test16 (x INTEGER PRIMARY KEY);
+  CREATE TRIGGER t16 AFTER INSERT ON test16 BEGIN INSERT INTO test16 VALUES (NEW.x + 1); END;
+  INSERT INTO test16 VALUES (1);
+  SELECT * FROM test16 ORDER BY x;
+} {1
+2}
+
+# Multiple UPDATE OF columns
+do_execsql_test_on_specific_db {:memory:} trigger-update-of-multiple {
+  CREATE TABLE test17 (x INTEGER PRIMARY KEY, y TEXT, z TEXT);
+  CREATE TABLE log17 (msg TEXT);
+  INSERT INTO test17 VALUES (1, 'a', 'b');
+  CREATE TRIGGER t17 AFTER UPDATE OF y, z ON test17 BEGIN INSERT INTO log17 VALUES ('updated'); END;
+  UPDATE test17 SET y = 'c' WHERE x = 1;
+  SELECT COUNT(*) FROM log17;
+  UPDATE test17 SET x = 2 WHERE x = 1;
+  SELECT COUNT(*) FROM log17;
+} {1
+1}
+
+# Complex WHEN clause with AND
+do_execsql_test_on_specific_db {:memory:} trigger-when-complex {
+  CREATE TABLE test18 (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log18 (x INTEGER);
+  CREATE TRIGGER t18 BEFORE INSERT ON test18 WHEN NEW.y > 5 AND NEW.y < 10 BEGIN INSERT INTO log18 VALUES (NEW.x); END;
+  INSERT INTO test18 VALUES (1, 3);
+  INSERT INTO test18 VALUES (2, 7);
+  INSERT INTO test18 VALUES (3, 12);
+  SELECT * FROM log18;
+} {2}
+
+# Nested triggers - trigger firing another trigger
+do_execsql_test_on_specific_db {:memory:} trigger-nested {
+  CREATE TABLE test19 (x INTEGER PRIMARY KEY);
+  CREATE TABLE test20 (x INTEGER PRIMARY KEY);
+  CREATE TABLE log19 (msg TEXT);
+  CREATE TRIGGER t19 AFTER INSERT ON test19 BEGIN INSERT INTO test20 VALUES (NEW.x); END;
+  CREATE TRIGGER t20 AFTER INSERT ON test20 BEGIN INSERT INTO log19 VALUES ('t20 inserted: ' || NEW.x); END;
+  INSERT INTO test19 VALUES (1);
+  SELECT * FROM log19;
+} {"t20 inserted: 1"}
+
+# BEFORE INSERT inserting into same table (recursive)
+do_execsql_test_on_specific_db {:memory:} trigger-recursive-before-insert {
+  CREATE TABLE test21 (x INTEGER PRIMARY KEY);
+  CREATE TRIGGER t21 BEFORE INSERT ON test21 BEGIN INSERT INTO test21 VALUES (NEW.x + 100); END;
+  INSERT INTO test21 VALUES (1);
+  SELECT * FROM test21 ORDER BY x;
+} {1
+101}
+
+# AFTER UPDATE with WHEN clause and UPDATE OF
+do_execsql_test_on_specific_db {:memory:} trigger-update-of-when {
+  CREATE TABLE test22 (x INTEGER PRIMARY KEY, y TEXT);
+  CREATE TRIGGER t22 AFTER UPDATE OF y ON test22 WHEN OLD.y != NEW.y BEGIN UPDATE test22 SET y = UPPER(NEW.y) WHERE x = NEW.x; END;
+  INSERT INTO test22 VALUES (1, 'hello');
+  UPDATE test22 SET y = 'world' WHERE x = 1;
+  SELECT * FROM test22;
+} {1|WORLD}
+
+# Multiple statements in BEFORE INSERT trigger
+do_execsql_test_on_specific_db {:memory:} trigger-multiple-statements-before-insert {
+  CREATE TABLE test23 (x INTEGER PRIMARY KEY, y TEXT);
+  CREATE TABLE log23a (msg TEXT);
+  CREATE TABLE log23b (msg TEXT);
+  CREATE TRIGGER t23 BEFORE INSERT ON test23 BEGIN INSERT INTO log23a VALUES ('before1'); INSERT INTO log23b VALUES ('before2'); END;
+  INSERT INTO test23 VALUES (1, 'hello');
+  SELECT * FROM log23a;
+  SELECT * FROM log23b;
+} {before1
+before2}
+
+# Multiple statements in AFTER INSERT trigger
+do_execsql_test_on_specific_db {:memory:} trigger-multiple-statements-after-insert {
+  CREATE TABLE test24 (x INTEGER PRIMARY KEY, y TEXT);
+  CREATE TABLE log24a (msg TEXT);
+  CREATE TABLE log24b (msg TEXT);
+  CREATE TRIGGER t24 AFTER INSERT ON test24 BEGIN INSERT INTO log24a VALUES ('after1'); INSERT INTO log24b VALUES ('after2'); END;
+  INSERT INTO test24 VALUES (1, 'hello');
+  SELECT * FROM log24a;
+  SELECT * FROM log24b;
+} {after1
+after2}
+
+# Multiple statements in BEFORE UPDATE trigger
+do_execsql_test_on_specific_db {:memory:} trigger-multiple-statements-before-update {
+  CREATE TABLE test25 (x INTEGER PRIMARY KEY, y TEXT);
+  CREATE TABLE log25a (msg TEXT);
+  CREATE TABLE log25b (msg TEXT);
+  INSERT INTO test25 VALUES (1, 'hello');
+  CREATE TRIGGER t25 BEFORE UPDATE ON test25 BEGIN INSERT INTO log25a VALUES ('before_update1'); INSERT INTO log25b VALUES ('before_update2'); END;
+  UPDATE test25 SET y = 'world' WHERE x = 1;
+  SELECT * FROM log25a;
+  SELECT * FROM log25b;
+} {before_update1
+before_update2}
+
+# Multiple statements in AFTER UPDATE trigger
+do_execsql_test_on_specific_db {:memory:} trigger-multiple-statements-after-update {
+  CREATE TABLE test26 (x INTEGER PRIMARY KEY, y TEXT);
+  CREATE TABLE log26a (msg TEXT);
+  CREATE TABLE log26b (msg TEXT);
+  INSERT INTO test26 VALUES (1, 'hello');
+  CREATE TRIGGER t26 AFTER UPDATE ON test26 BEGIN INSERT INTO log26a VALUES ('after_update1'); INSERT INTO log26b VALUES ('after_update2'); END;
+  UPDATE test26 SET y = 'world' WHERE x = 1;
+  SELECT * FROM log26a;
+  SELECT * FROM log26b;
+} {after_update1
+after_update2}
+
+# Multiple statements in BEFORE DELETE trigger
+do_execsql_test_on_specific_db {:memory:} trigger-multiple-statements-before-delete {
+  CREATE TABLE test27 (x INTEGER PRIMARY KEY, y TEXT);
+  CREATE TABLE log27a (msg TEXT);
+  CREATE TABLE log27b (msg TEXT);
+  INSERT INTO test27 VALUES (1, 'hello');
+  CREATE TRIGGER t27 BEFORE DELETE ON test27 BEGIN INSERT INTO log27a VALUES ('before_delete1'); INSERT INTO log27b VALUES ('before_delete2'); END;
+  DELETE FROM test27 WHERE x = 1;
+  SELECT * FROM log27a;
+  SELECT * FROM log27b;
+} {before_delete1
+before_delete2}
+
+# Multiple statements in AFTER DELETE trigger
+do_execsql_test_on_specific_db {:memory:} trigger-multiple-statements-after-delete {
+  CREATE TABLE test28 (x INTEGER PRIMARY KEY, y TEXT);
+  CREATE TABLE log28a (msg TEXT);
+  CREATE TABLE log28b (msg TEXT);
+  INSERT INTO test28 VALUES (1, 'hello');
+  CREATE TRIGGER t28 AFTER DELETE ON test28 BEGIN INSERT INTO log28a VALUES ('after_delete1'); INSERT INTO log28b VALUES ('after_delete2'); END;
+  DELETE FROM test28 WHERE x = 1;
+  SELECT * FROM log28a;
+  SELECT * FROM log28b;
+} {after_delete1
+after_delete2}
+
+# Multiple statements with mixed operations in BEFORE INSERT trigger
+do_execsql_test_on_specific_db {:memory:} trigger-multiple-statements-mixed-before-insert {
+  CREATE TABLE test29 (x INTEGER PRIMARY KEY, y TEXT);
+  CREATE TABLE log29 (x INTEGER, y TEXT);
+  CREATE TABLE counter29 (cnt INTEGER);
+  INSERT INTO counter29 VALUES (0);
+  CREATE TRIGGER t29 BEFORE INSERT ON test29 BEGIN INSERT INTO log29 VALUES (NEW.x, NEW.y); UPDATE counter29 SET cnt = cnt + 1; END;
+  INSERT INTO test29 VALUES (1, 'hello');
+  INSERT INTO test29 VALUES (2, 'world');
+  SELECT * FROM log29 ORDER BY x;
+  SELECT * FROM counter29;
+} {1|hello
+2|world
+2}
+
+# Multiple statements with conditional logic in trigger
+do_execsql_test_on_specific_db {:memory:} trigger-multiple-statements-conditional {
+  CREATE TABLE test30 (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log30 (msg TEXT);
+  CREATE TRIGGER t30 AFTER INSERT ON test30 BEGIN INSERT INTO log30 VALUES ('inserted: ' || NEW.x); INSERT INTO log30 VALUES ('value: ' || NEW.y); INSERT INTO log30 VALUES ('done'); END;
+  INSERT INTO test30 VALUES (1, 10);
+  INSERT INTO test30 VALUES (2, 20);
+  SELECT * FROM log30 ORDER BY msg;
+} {done
+done
+"inserted: 1"
+"inserted: 2"
+"value: 10"
+"value: 20"}
+
+# Trigger that updates the same row being updated (recursive update)
+do_execsql_test_on_specific_db {:memory:} trigger-update-same-row {
+  CREATE TABLE test31 (x INTEGER PRIMARY KEY, y INTEGER, z INTEGER);
+  INSERT INTO test31 VALUES (1, 10, 0);
+  CREATE TRIGGER t31 AFTER UPDATE OF y ON test31 BEGIN UPDATE test31 SET z = z + 1 WHERE x = NEW.x; END;
+  UPDATE test31 SET y = 20 WHERE x = 1;
+  SELECT * FROM test31;
+} {1|20|1}
+
+# Trigger that deletes the row being inserted
+do_execsql_test_on_specific_db {:memory:} trigger-delete-inserted-row {
+  CREATE TABLE test32 (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log32 (msg TEXT);
+  CREATE TRIGGER t32 AFTER INSERT ON test32 BEGIN DELETE FROM test32 WHERE x = NEW.x AND NEW.y < 0; INSERT INTO log32 VALUES ('processed: ' || NEW.x); END;
+  INSERT INTO test32 VALUES (1, 10);
+  INSERT INTO test32 VALUES (2, -5);
+  SELECT * FROM test32;
+  SELECT * FROM log32 ORDER BY msg;
+} {1|10
+"processed: 1"
+"processed: 2"}
+
+# Trigger chain: INSERT triggers UPDATE which triggers DELETE
+do_execsql_test_on_specific_db {:memory:} trigger-chain-insert-update-delete {
+  CREATE TABLE test34 (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log34 (msg TEXT);
+  CREATE TRIGGER t34a AFTER INSERT ON test34 BEGIN UPDATE test34 SET y = y + 1 WHERE x = NEW.x; END;
+  CREATE TRIGGER t34b AFTER UPDATE ON test34 BEGIN DELETE FROM test34 WHERE y > 100; INSERT INTO log34 VALUES ('updated: ' || NEW.x); END;
+  INSERT INTO test34 VALUES (1, 50);
+  INSERT INTO test34 VALUES (2, 100);
+  SELECT * FROM test34 ORDER BY x;
+  SELECT * FROM log34 ORDER BY msg;
+} {1|51
+"updated: 1"
+"updated: 2"}
+
+# Trigger that inserts into the same table (recursive insert)
+do_execsql_test_on_specific_db {:memory:} trigger-recursive-insert {
+  CREATE TABLE test35 (x INTEGER PRIMARY KEY, y INTEGER, depth INTEGER);
+  CREATE TRIGGER t35 AFTER INSERT ON test35 WHEN NEW.depth < 3 BEGIN INSERT INTO test35 VALUES (NEW.x * 10, NEW.y + 1, NEW.depth + 1); END;
+  INSERT INTO test35 VALUES (1, 0, 0);
+  SELECT * FROM test35 ORDER BY x;
+} {1|0|0
+10|1|1}
+
+# Trigger that updates OLD values in BEFORE UPDATE
+do_execsql_test_on_specific_db {:memory:} trigger-update-old-reference {
+  CREATE TABLE test36 (x INTEGER PRIMARY KEY, y INTEGER, z INTEGER);
+  CREATE TABLE log36 (old_y INTEGER, new_y INTEGER);
+  INSERT INTO test36 VALUES (1, 10, 0);
+  CREATE TRIGGER t36 BEFORE UPDATE OF y ON test36 BEGIN INSERT INTO log36 VALUES (OLD.y, NEW.y); UPDATE test36 SET z = OLD.y + NEW.y WHERE x = NEW.x; END;
+  UPDATE test36 SET y = 20 WHERE x = 1;
+  SELECT * FROM test36;
+  SELECT * FROM log36;
+} {1|20|30
+10|20}
+
+# Trigger that causes constraint violation in another table
+do_execsql_test_on_specific_db {:memory:} trigger-constraint-violation {
+  CREATE TABLE test37a (x INTEGER PRIMARY KEY);
+  CREATE TABLE test37b (x INTEGER PRIMARY KEY, y INTEGER);
+  INSERT INTO test37b VALUES (1, 100);
+  CREATE TRIGGER t37 AFTER INSERT ON test37a BEGIN INSERT OR IGNORE INTO test37b VALUES (NEW.x, NEW.x * 10); END;
+  INSERT INTO test37a VALUES (1);
+  SELECT * FROM test37b ORDER BY x;
+} {1|100}
+
+# Multiple triggers on same event with interdependencies
+do_execsql_test_on_specific_db {:memory:} trigger-multiple-interdependent {
+  CREATE TABLE test38 (x INTEGER PRIMARY KEY, y INTEGER, z INTEGER);
+  CREATE TRIGGER t38a AFTER INSERT ON test38 BEGIN UPDATE test38 SET y = 100 WHERE x = NEW.x; END;
+  CREATE TRIGGER t38b AFTER INSERT ON test38 BEGIN UPDATE test38 SET z = 200 WHERE x = NEW.x; END;
+  INSERT INTO test38 VALUES (1, 10, 20);
+  SELECT * FROM test38;
+} {1|100|200}
+
+# Trigger that references both OLD and NEW in UPDATE
+do_execsql_test_on_specific_db {:memory:} trigger-old-new-arithmetic {
+  CREATE TABLE test39 (x INTEGER PRIMARY KEY, y INTEGER, delta INTEGER);
+  INSERT INTO test39 VALUES (1, 10, 0);
+  CREATE TRIGGER t39 BEFORE UPDATE OF y ON test39 BEGIN UPDATE test39 SET delta = NEW.y - OLD.y WHERE x = NEW.x; END;
+  UPDATE test39 SET y = 25 WHERE x = 1;
+  SELECT * FROM test39;
+} {1|25|15}
+
+# Trigger that performs DELETE based on NEW values
+do_execsql_test_on_specific_db {:memory:} trigger-delete-on-insert-condition {
+  CREATE TABLE test40 (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE archive40 (x INTEGER, y INTEGER);
+  INSERT INTO test40 VALUES (1, 10);
+  INSERT INTO test40 VALUES (2, 20);
+  CREATE TRIGGER t40 AFTER INSERT ON test40 BEGIN DELETE FROM test40 WHERE y < NEW.y; INSERT INTO archive40 SELECT * FROM test40 WHERE x = NEW.x; END;
+  INSERT INTO test40 VALUES (3, 15);
+  SELECT * FROM test40 ORDER BY x;
+  SELECT * FROM archive40 ORDER BY x;
+} {2|20
+3|15
+3|15}
+
+# Trigger with WHEN clause that modifies the condition column
+do_execsql_test_on_specific_db {:memory:} trigger-when-clause-modification {
+  CREATE TABLE test41 (x INTEGER PRIMARY KEY, y INTEGER, processed INTEGER DEFAULT 0);
+  CREATE TRIGGER t41 AFTER INSERT ON test41 WHEN NEW.y > 50 BEGIN UPDATE test41 SET processed = 1 WHERE x = NEW.x; END;
+  INSERT INTO test41 (x, y) VALUES (1, 30);
+  INSERT INTO test41 (x, y) VALUES (2, 60);
+  INSERT INTO test41 (x, y) VALUES (3, 70);
+  SELECT * FROM test41 ORDER BY x;
+} {1|30|0
+2|60|1
+3|70|1}
+
+# Trigger that creates circular dependency between two tables
+do_execsql_test_on_specific_db {:memory:} trigger-circular-dependency {
+  CREATE TABLE test42a (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE test42b (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TRIGGER t42a AFTER INSERT ON test42a BEGIN INSERT OR IGNORE INTO test42b VALUES (NEW.x, NEW.y + 1); END;
+  CREATE TRIGGER t42b AFTER INSERT ON test42b BEGIN INSERT OR IGNORE INTO test42a VALUES (NEW.x + 100, NEW.y + 1); END;
+  INSERT INTO test42a VALUES (1, 10);
+  SELECT * FROM test42a ORDER BY x;
+  SELECT * FROM test42b ORDER BY x;
+} {1|10
+101|12
+1|11}
+
+# BEFORE trigger modifying primary key value
+do_execsql_test_on_specific_db {:memory:} trigger-before-modify-primary-key {
+  CREATE TABLE test43 (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TRIGGER t43 BEFORE INSERT ON test43 BEGIN UPDATE test43 SET x = NEW.x + 1000 WHERE x = NEW.x; END;
+  INSERT INTO test43 VALUES (1, 10);
+  SELECT * FROM test43;
+} {1|10}
+
+# UPDATE OF trigger modifying the same column it watches
+do_execsql_test_on_specific_db {:memory:} trigger-update-of-modify-same-column {
+  CREATE TABLE test44 (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log44 (msg TEXT);
+  INSERT INTO test44 VALUES (1, 10);
+  CREATE TRIGGER t44 AFTER UPDATE OF y ON test44 BEGIN UPDATE test44 SET y = y * 2 WHERE x = NEW.x; INSERT INTO log44 VALUES ('triggered'); END;
+  UPDATE test44 SET y = 5 WHERE x = 1;
+  SELECT * FROM test44;
+  SELECT COUNT(*) FROM log44;
+} {1|10
+1}
+
+# BEFORE trigger modifying column used in UPDATE OF clause
+do_execsql_test_on_specific_db {:memory:} trigger-before-modify-update-of-column {
+  CREATE TABLE test45 (x INTEGER PRIMARY KEY, y INTEGER, z INTEGER);
+  CREATE TABLE log45 (msg TEXT);
+  INSERT INTO test45 VALUES (1, 10, 0);
+  CREATE TRIGGER t45a BEFORE UPDATE OF y ON test45 BEGIN UPDATE test45 SET y = y + 100 WHERE x = NEW.x; END;
+  CREATE TRIGGER t45b AFTER UPDATE OF y ON test45 BEGIN INSERT INTO log45 VALUES ('y=' || NEW.y); END;
+  UPDATE test45 SET y = 20 WHERE x = 1;
+  SELECT * FROM test45;
+  SELECT * FROM log45;
+} {1|20|0
+y=110
+y=20}
+
+# Trigger modifying column used in WHEN clause
+do_execsql_test_on_specific_db {:memory:} trigger-modify-when-clause-column {
+  CREATE TABLE test47 (x INTEGER PRIMARY KEY, y INTEGER, z INTEGER);
+  CREATE TABLE log47 (msg TEXT);
+  INSERT INTO test47 VALUES (1, 10, 0);
+  CREATE TRIGGER t47 BEFORE UPDATE ON test47 WHEN NEW.y > 5 BEGIN UPDATE test47 SET y = y - 10 WHERE x = NEW.x; INSERT INTO log47 VALUES ('modified'); END;
+  UPDATE test47 SET y = 15 WHERE x = 1;
+  SELECT * FROM test47;
+  SELECT COUNT(*) FROM log47;
+} {1|15|0
+1}
+
+# Trigger causing unique constraint violation with INSERT OR IGNORE
+do_execsql_test_on_specific_db {:memory:} trigger-unique-violation-ignore {
+  CREATE TABLE test48 (x INTEGER PRIMARY KEY, y INTEGER UNIQUE);
+  CREATE TABLE log48 (x INTEGER);
+  INSERT INTO test48 VALUES (1, 100);
+  CREATE TRIGGER t48 AFTER INSERT ON test48 BEGIN INSERT OR IGNORE INTO test48 VALUES (NEW.x + 1, NEW.y); INSERT INTO log48 VALUES (NEW.x); END;
+  INSERT INTO test48 VALUES (2, 200);
+  SELECT * FROM test48 ORDER BY x;
+  SELECT * FROM log48 ORDER BY x;
+} {1|100
+2|200
+2}
+
+# Multiple triggers modifying same column in different ways
+do_execsql_test_on_specific_db {:memory:} trigger-multiple-modify-same-column {
+  CREATE TABLE test49 (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TRIGGER t49a BEFORE INSERT ON test49 BEGIN UPDATE test49 SET y = y + 1 WHERE x = NEW.x; END;
+  CREATE TRIGGER t49b BEFORE INSERT ON test49 BEGIN UPDATE test49 SET y = y * 2 WHERE x = NEW.x; END;
+  CREATE TRIGGER t49c BEFORE INSERT ON test49 BEGIN UPDATE test49 SET y = y + 10 WHERE x = NEW.x; END;
+  INSERT INTO test49 VALUES (1, 5);
+  SELECT * FROM test49;
+} {1|5}
+
+# BEFORE trigger modifying NEW values used in WHEN clause
+do_execsql_test_on_specific_db {:memory:} trigger-before-modify-new-in-when {
+  CREATE TABLE test51 (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log51 (msg TEXT);
+  INSERT INTO test51 VALUES (1, 5);
+  CREATE TRIGGER t51a BEFORE UPDATE ON test51 BEGIN UPDATE test51 SET y = y + 20 WHERE x = NEW.x; END;
+  CREATE TRIGGER t51b AFTER UPDATE ON test51 WHEN NEW.y > 10 BEGIN INSERT INTO log51 VALUES ('y=' || NEW.y); END;
+  UPDATE test51 SET y = 8 WHERE x = 1;
+  SELECT * FROM test51;
+  SELECT * FROM log51;
+} {1|8
+y=25}
+
+# UPDATE OF on non-existent column (should be silently ignored)
+do_execsql_test_on_specific_db {:memory:} trigger-update-of-nonexistent-column {
+  CREATE TABLE test52 (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log52 (msg TEXT);
+  INSERT INTO test52 VALUES (1, 10);
+  CREATE TRIGGER t52 AFTER UPDATE OF nonexistent ON test52 BEGIN INSERT INTO log52 VALUES ('triggered'); END;
+  UPDATE test52 SET y = 20 WHERE x = 1;
+  SELECT COUNT(*) FROM log52;
+} {0}
+
+# Trigger modifying same column multiple times in one trigger body
+do_execsql_test_on_specific_db {:memory:} trigger-modify-column-multiple-times {
+  CREATE TABLE test53 (x INTEGER PRIMARY KEY, y INTEGER);
+  INSERT INTO test53 VALUES (1, 10);
+  CREATE TRIGGER t53 AFTER UPDATE OF y ON test53 BEGIN UPDATE test53 SET y = y + 1 WHERE x = NEW.x; UPDATE test53 SET y = y * 2 WHERE x = NEW.x; UPDATE test53 SET y = y + 5 WHERE x = NEW.x; END;
+  UPDATE test53 SET y = 5 WHERE x = 1;
+  SELECT * FROM test53;
+} {1|17}
+
+# Trigger that modifies rowid indirectly through updates
+do_execsql_test_on_specific_db {:memory:} trigger-modify-rowid-indirect {
+  CREATE TABLE test55 (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log55 (old_rowid INTEGER, new_rowid INTEGER);
+  INSERT INTO test55 VALUES (1, 10);
+  INSERT INTO test55 VALUES (2, 20);
+  CREATE TRIGGER t55 AFTER UPDATE ON test55 BEGIN INSERT INTO log55 VALUES (OLD.x, NEW.x); END;
+  UPDATE test55 SET x = 3 WHERE x = 1;
+  SELECT * FROM test55 ORDER BY x;
+  SELECT * FROM log55;
+} {2|20
+3|10
+1|3}
+
+# Trigger that references OLD.rowid and NEW.rowid with rowid alias column
+do_execsql_test_on_specific_db {:memory:} trigger-rowid-alias-old-new {
+  CREATE TABLE test55b (id INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log55b (old_id INTEGER, new_id INTEGER, old_rowid INTEGER, new_rowid INTEGER);
+  INSERT INTO test55b VALUES (1, 10);
+  INSERT INTO test55b VALUES (2, 20);
+  CREATE TRIGGER t55b AFTER UPDATE ON test55b BEGIN INSERT INTO log55b VALUES (OLD.id, NEW.id, OLD.rowid, NEW.rowid); END;
+  UPDATE test55b SET id = 3 WHERE id = 1;
+  SELECT * FROM test55b ORDER BY id;
+  SELECT * FROM log55b;
+} {2|20
+3|10
+1|3|1|3}
+
+# Trigger with BEFORE UPDATE that modifies rowid alias in WHEN clause
+do_execsql_test_on_specific_db {:memory:} trigger-before-update-rowid-alias-when {
+  CREATE TABLE test55c (id INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log55c (msg TEXT);
+  INSERT INTO test55c VALUES (1, 10);
+  CREATE TRIGGER t55c BEFORE UPDATE ON test55c WHEN NEW.id > 5 BEGIN UPDATE test55c SET y = y + 100 WHERE id = NEW.id; END;
+  UPDATE test55c SET id = 10, y = 20 WHERE id = 1;
+  SELECT * FROM test55c;
+  SELECT COUNT(*) FROM log55c;
+} {10|20
+0}
+
+# Trigger referencing OLD.rowid in DELETE with rowid alias column
+do_execsql_test_on_specific_db {:memory:} trigger-delete-old-rowid-alias {
+  CREATE TABLE test55d (pk INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log55d (deleted_pk INTEGER, deleted_rowid INTEGER);
+  INSERT INTO test55d VALUES (1, 10);
+  INSERT INTO test55d VALUES (2, 20);
+  CREATE TRIGGER t55d AFTER DELETE ON test55d BEGIN INSERT INTO log55d VALUES (OLD.pk, OLD.rowid); END;
+  DELETE FROM test55d WHERE pk = 1;
+  SELECT * FROM test55d;
+  SELECT * FROM log55d;
+} {2|20
+1|1}
+
+# Trigger with NEW.rowid in INSERT with rowid alias
+do_execsql_test_on_specific_db {:memory:} trigger-insert-new-rowid-alias {
+  CREATE TABLE test55e (myid INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log55e (new_myid INTEGER, new_rowid INTEGER);
+  CREATE TRIGGER t55e AFTER INSERT ON test55e BEGIN INSERT INTO log55e VALUES (NEW.myid, NEW.rowid); END;
+  INSERT INTO test55e VALUES (5, 50);
+  INSERT INTO test55e VALUES (10, 100);
+  SELECT * FROM test55e ORDER BY myid;
+  SELECT * FROM log55e ORDER BY new_myid;
+} {5|50
+10|100
+5|5
+10|10}
+
+# Trigger modifying rowid through UPDATE with complex WHERE using rowid alias
+do_execsql_test_on_specific_db {:memory:} trigger-update-rowid-complex-where {
+  CREATE TABLE test55f (rid INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log55f (old_rid INTEGER, new_rid INTEGER);
+  INSERT INTO test55f VALUES (1, 10);
+  INSERT INTO test55f VALUES (2, 20);
+  INSERT INTO test55f VALUES (3, 30);
+  CREATE TRIGGER t55f AFTER UPDATE ON test55f BEGIN INSERT INTO log55f VALUES (OLD.rid, NEW.rid); UPDATE test55f SET y = y + 1 WHERE rid = NEW.rid; END;
+  UPDATE test55f SET rid = 100 WHERE rid = 2;
+  SELECT * FROM test55f ORDER BY rid;
+  SELECT * FROM log55f;
+} {1|10
+3|30
+100|21
+2|100}
+
+# Trigger using both rowid and rowid alias in same expression
+do_execsql_test_on_specific_db {:memory:} trigger-rowid-and-alias-mixed {
+  CREATE TABLE test55g (id INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log55g (id_val INTEGER, rowid_val INTEGER, match INTEGER);
+  INSERT INTO test55g VALUES (1, 10);
+  CREATE TRIGGER t55g AFTER INSERT ON test55g BEGIN INSERT INTO log55g VALUES (NEW.id, NEW.rowid, NEW.id = NEW.rowid); END;
+  INSERT INTO test55g VALUES (5, 50);
+  SELECT * FROM log55g;
+} {5|5|1}
+
+# Trigger that causes cascading updates through multiple tables
+do_execsql_test_on_specific_db {:memory:} trigger-cascading-updates {
+  CREATE TABLE test57a (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE test57b (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log57 (msg TEXT);
+  INSERT INTO test57a VALUES (1, 10);
+  INSERT INTO test57b VALUES (1, 100);
+  CREATE TRIGGER t57a AFTER UPDATE ON test57a BEGIN UPDATE test57b SET y = NEW.y * 10 WHERE x = NEW.x; END;
+  CREATE TRIGGER t57b AFTER UPDATE ON test57b BEGIN INSERT INTO log57 VALUES ('b updated: ' || NEW.y); END;
+  UPDATE test57a SET y = 20 WHERE x = 1;
+  SELECT * FROM test57a;
+  SELECT * FROM test57b;
+  SELECT * FROM log57;
+} {1|20
+1|200
+"b updated: 200"}
+
+# Trigger modifying columns used in unique constraint
+do_execsql_test_on_specific_db {:memory:} trigger-modify-unique-column {
+  CREATE TABLE test58 (x INTEGER PRIMARY KEY, y INTEGER UNIQUE);
+  CREATE TABLE log58 (msg TEXT);
+  INSERT INTO test58 VALUES (1, 10);
+  INSERT INTO test58 VALUES (2, 20);
+  CREATE TRIGGER t58 AFTER UPDATE ON test58 BEGIN UPDATE test58 SET y = y + 1 WHERE x != NEW.x; INSERT INTO log58 VALUES ('updated'); END;
+  UPDATE test58 SET y = 15 WHERE x = 1;
+  SELECT * FROM test58 ORDER BY x;
+  SELECT COUNT(*) FROM log58;
+} {1|15
+2|21
+1}
+
+# BEFORE INSERT trigger that modifies NEW.x before insertion
+do_execsql_test_on_specific_db {:memory:} trigger-before-insert-modify-new {
+  CREATE TABLE test59 (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TRIGGER t59 BEFORE INSERT ON test59 BEGIN UPDATE test59 SET x = NEW.x + 100 WHERE x = NEW.x; END;
+  INSERT INTO test59 VALUES (1, 10);
+  SELECT * FROM test59;
+} {1|10}
+
+# Trigger with UPDATE OF multiple columns, modifying one of them
+do_execsql_test_on_specific_db {:memory:} trigger-update-of-multiple-modify-one {
+  CREATE TABLE test60 (x INTEGER PRIMARY KEY, y INTEGER, z INTEGER);
+  CREATE TABLE log60 (msg TEXT);
+  INSERT INTO test60 VALUES (1, 10, 100);
+  CREATE TRIGGER t60 AFTER UPDATE OF y, z ON test60 BEGIN UPDATE test60 SET y = y + 50 WHERE x = NEW.x; INSERT INTO log60 VALUES ('triggered'); END;
+  UPDATE test60 SET y = 20 WHERE x = 1;
+  SELECT * FROM test60;
+  SELECT COUNT(*) FROM log60;
+  UPDATE test60 SET z = 200 WHERE x = 1;
+  SELECT * FROM test60;
+  SELECT COUNT(*) FROM log60;
+} {1|70|100
+1
+1|120|200
+2}
+
+# Trigger modifying column that's part of composite unique constraint
+do_execsql_test_on_specific_db {:memory:} trigger-modify-composite-unique {
+  CREATE TABLE test62 (x INTEGER, y INTEGER, UNIQUE(x, y));
+  CREATE TABLE log62 (msg TEXT);
+  INSERT INTO test62 VALUES (1, 10);
+  INSERT INTO test62 VALUES (2, 20);
+  CREATE TRIGGER t62 AFTER UPDATE ON test62 BEGIN UPDATE test62 SET y = y + 1 WHERE x = NEW.x + 1; INSERT INTO log62 VALUES ('updated'); END;
+  UPDATE test62 SET y = 15 WHERE x = 1;
+  SELECT * FROM test62 ORDER BY x;
+  SELECT COUNT(*) FROM log62;
+} {1|15
+2|21
+1}
+
+# Trigger with WHEN clause that becomes false after BEFORE trigger modification
+do_execsql_test_on_specific_db {:memory:} trigger-when-becomes-false-after-before {
+  CREATE TABLE test63 (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TABLE log63 (msg TEXT);
+  INSERT INTO test63 VALUES (1, 10);
+  CREATE TRIGGER t63a BEFORE UPDATE ON test63 BEGIN UPDATE test63 SET y = y - 15 WHERE x = NEW.x; END;
+  CREATE TRIGGER t63b AFTER UPDATE ON test63 WHEN NEW.y > 0 BEGIN INSERT INTO log63 VALUES ('y=' || NEW.y); END;
+  UPDATE test63 SET y = 20 WHERE x = 1;
+  SELECT * FROM test63;
+  SELECT COUNT(*) FROM log63;
+} {1|20
+1}
+
+# Trigger that inserts into same table with different rowid
+do_execsql_test_on_specific_db {:memory:} trigger-recursive-different-rowid {
+  CREATE TABLE test64 (x INTEGER PRIMARY KEY, y INTEGER);
+  CREATE TRIGGER t64 AFTER INSERT ON test64 WHEN NEW.y < 100 BEGIN INSERT INTO test64 VALUES (NEW.x + 1000, NEW.y + 10); END;
+  INSERT INTO test64 VALUES (1, 5);
+  INSERT INTO test64 VALUES (2, 50);
+  SELECT * FROM test64 ORDER BY x;
+} {1|5
+2|50
+1001|15
+1002|60}
+
+# Trigger modifying primary key through UPDATE in BEFORE trigger
+do_execsql_test_on_specific_db {:memory:} trigger-before-update-primary-key {
+  CREATE TABLE test65 (x INTEGER PRIMARY KEY, y INTEGER);
+  INSERT INTO test65 VALUES (1, 10);
+  CREATE TRIGGER t65 BEFORE UPDATE ON test65 BEGIN UPDATE test65 SET x = NEW.x + 100 WHERE x = OLD.x; END;
+  UPDATE test65 SET y = 20 WHERE x = 1;
+  SELECT * FROM test65 ORDER BY x;
+} {101|10}
+
+# Trigger modifying row during BEFORE UPDATE - parent expression behavior
+# The parent UPDATE's SET clause expressions (c0 = c1+1) use OLD values for columns
+# referenced in the expression (c1), but the final row gets the modified values from
+# the BEFORE trigger for columns not in the parent's SET clause (c1, c2).
+do_execsql_test_on_specific_db {:memory:} trigger-before-update-parent-expression-old-values {
+  CREATE TABLE test66 (c0 INTEGER, c1 INTEGER, c2 INTEGER);
+  CREATE TRIGGER tu66 BEFORE UPDATE ON test66 BEGIN UPDATE test66 SET c1=666, c2=666; END;
+  INSERT INTO test66 VALUES (1,1,1);
+  UPDATE test66 SET c0 = c1+1;
+  SELECT * FROM test66;
+} {2|666|666}
+
+# Multiple BEFORE INSERT triggers - last added trigger fires first
+# SQLite evaluates triggers in reverse order of creation (LIFO)
+do_execsql_test_on_specific_db {:memory:} trigger-multiple-before-insert-lifo {
+  CREATE TABLE t67(c0 INTEGER, c1 INTEGER, c2 INTEGER, whodunnit TEXT);
+  CREATE TRIGGER t67_first BEFORE INSERT ON t67 BEGIN INSERT INTO t67 VALUES (NEW.c0+1, NEW.c1+2, NEW.c2+3, 't67_first'); END;
+  CREATE TRIGGER t67_second BEFORE INSERT ON t67 BEGIN INSERT INTO t67 VALUES (NEW.c0+2, NEW.c1+3, NEW.c2+4, 't67_second'); END;
+  INSERT INTO t67 VALUES (1, 1, 1, 'jussi');
+  SELECT rowid, * FROM t67 ORDER BY rowid;
+} {1|4|6|8|t67_first
+2|3|4|5|t67_second
+3|4|6|8|t67_second
+4|2|3|4|t67_first
+5|1|1|1|jussi}

tests/fuzz/mod.rs

@@ -651,16 +651,21 @@ mod fuzz_tests {
 
     #[test]
     #[allow(unused_assignments)]
-    pub fn fk_deferred_constraints_fuzz() {
+    pub fn fk_deferred_constraints_and_triggers_fuzz() {
+        let _ = tracing_subscriber::fmt::try_init();
         let _ = env_logger::try_init();
         let (mut rng, seed) = rng_from_time_or_env();
-        println!("fk_deferred_constraints_fuzz seed: {seed}");
+        println!("fk_deferred_constraints_and_triggers_fuzz seed: {seed}");
 
         const OUTER_ITERS: usize = 10;
         const INNER_ITERS: usize = 100;
 
         for outer in 0..OUTER_ITERS {
-            println!("fk_deferred_constraints_fuzz {}/{}", outer + 1, OUTER_ITERS);
+            println!(
+                "fk_deferred_constraints_and_triggers_fuzz {}/{}",
+                outer + 1,
+                OUTER_ITERS
+            );
 
             let limbo_db = TempDatabase::new_empty();
             let sqlite_db = TempDatabase::new_empty();
@@ -757,6 +762,99 @@ mod fuzz_tests {
                 }
             }
 
+            // Add triggers on every outer iteration (max 2 triggers)
+            // Create a log table for trigger operations
+            let s = log_and_exec(
+                "CREATE TABLE trigger_log(action TEXT, table_name TEXT, id_val INT, extra_val INT)",
+            );
+            limbo_exec_rows(&limbo_db, &limbo, &s);
+            sqlite.execute(&s, params![]).unwrap();
+
+            // Create a stats table for tracking operations
+            let s = log_and_exec("CREATE TABLE trigger_stats(op_type TEXT PRIMARY KEY, count INT)");
+            limbo_exec_rows(&limbo_db, &limbo, &s);
+            sqlite.execute(&s, params![]).unwrap();
+
+            // Define all available trigger types
+            let trigger_definitions: Vec<&str> = vec![
+                // BEFORE INSERT trigger on parent - logs and potentially creates a child
+                "CREATE TRIGGER trig_parent_before_insert BEFORE INSERT ON parent BEGIN
+                 INSERT INTO trigger_log VALUES ('BEFORE_INSERT', 'parent', NEW.id, NEW.a);
+                 INSERT INTO trigger_stats VALUES ('parent_insert', 1) ON CONFLICT(op_type) DO UPDATE SET count=count+1;
+                 -- Sometimes create a deferred child referencing this parent
+                 INSERT INTO child_deferred VALUES (NEW.id + 10000, NEW.id, NEW.a);
+                END",
+                // AFTER INSERT trigger on child_deferred - logs and updates parent
+                "CREATE TRIGGER trig_child_deferred_after_insert AFTER INSERT ON child_deferred BEGIN
+                 INSERT INTO trigger_log VALUES ('AFTER_INSERT', 'child_deferred', NEW.id, NEW.pid);
+                 INSERT INTO trigger_stats VALUES ('child_deferred_insert', 1) ON CONFLICT(op_type) DO UPDATE SET count=count+1;
+                 -- Update parent's 'a' column if parent exists
+                 UPDATE parent SET a = a + 1 WHERE id = NEW.pid;
+                END",
+                // BEFORE UPDATE OF 'a' on parent - logs and modifies the update
+                "CREATE TRIGGER trig_parent_before_update_a BEFORE UPDATE OF a ON parent BEGIN
+                 INSERT INTO trigger_log VALUES ('BEFORE_UPDATE_A', 'parent', OLD.id, OLD.a);
+                 INSERT INTO trigger_stats VALUES ('parent_update_a', 1) ON CONFLICT(op_type) DO UPDATE SET count=count+1;
+                 -- Also update 'b' column when 'a' is updated
+                 UPDATE parent SET b = NEW.a * 2 WHERE id = NEW.id;
+                END",
+                // AFTER UPDATE OF 'pid' on child_deferred - logs and creates/updates related records
+                "CREATE TRIGGER trig_child_deferred_after_update_pid AFTER UPDATE OF pid ON child_deferred BEGIN
+                 INSERT INTO trigger_log VALUES ('AFTER_UPDATE_PID', 'child_deferred', NEW.id, NEW.pid);
+                 INSERT INTO trigger_stats VALUES ('child_deferred_update_pid', 1) ON CONFLICT(op_type) DO UPDATE SET count=count+1;
+                 -- Create a child_immediate referencing the new parent
+                 INSERT INTO child_immediate VALUES (NEW.id + 20000, NEW.pid, NEW.x);
+                 -- Update parent's 'b' column
+                 UPDATE parent SET b = b + 1 WHERE id = NEW.pid;
+                END",
+                // BEFORE DELETE on parent - logs and cascades to children
+                "CREATE TRIGGER trig_parent_before_delete BEFORE DELETE ON parent BEGIN
+                 INSERT INTO trigger_log VALUES ('BEFORE_DELETE', 'parent', OLD.id, OLD.a);
+                 INSERT INTO trigger_stats VALUES ('parent_delete', 1) ON CONFLICT(op_type) DO UPDATE SET count=count+1;
+                 -- Delete all children that reference the deleted parent
+                 DELETE FROM child_deferred WHERE pid = OLD.id;
+                END",
+                // AFTER DELETE on child_deferred - logs and updates parent stats
+                "CREATE TRIGGER trig_child_deferred_after_delete AFTER DELETE ON child_deferred BEGIN
+                 INSERT INTO trigger_log VALUES ('AFTER_DELETE', 'child_deferred', OLD.id, OLD.pid);
+                 INSERT INTO trigger_stats VALUES ('child_deferred_delete', 1) ON CONFLICT(op_type) DO UPDATE SET count=count+1;
+                 -- Update parent's 'a' column
+                 UPDATE parent SET a = a - 1 WHERE id = OLD.pid;
+                END",
+                // BEFORE INSERT on child_immediate - logs, creates parent if needed, updates stats
+                "CREATE TRIGGER trig_child_immediate_before_insert BEFORE INSERT ON child_immediate BEGIN
+                 INSERT INTO trigger_log VALUES ('BEFORE_INSERT', 'child_immediate', NEW.id, NEW.pid);
+                 INSERT INTO trigger_stats VALUES ('child_immediate_insert', 1) ON CONFLICT(op_type) DO UPDATE SET count=count+1;
+                 -- Create parent if it doesn't exist (with a default value)
+                 INSERT OR IGNORE INTO parent VALUES (NEW.pid, NEW.y, NEW.y * 2);
+                 -- Update parent's 'a' column
+                 UPDATE parent SET a = a + NEW.y WHERE id = NEW.pid;
+                END",
+                // AFTER UPDATE OF 'y' on child_immediate - logs and cascades updates
+                "CREATE TRIGGER trig_child_immediate_after_update_y AFTER UPDATE OF y ON child_immediate BEGIN
+                 INSERT INTO trigger_log VALUES ('AFTER_UPDATE_Y', 'child_immediate', NEW.id, NEW.y);
+                 INSERT INTO trigger_stats VALUES ('child_immediate_update_y', 1) ON CONFLICT(op_type) DO UPDATE SET count=count+1;
+                 -- Update parent's 'a' based on the change
+                 UPDATE parent SET a = a + (NEW.y - OLD.y) WHERE id = NEW.pid;
+                 -- Also create a deferred child referencing the same parent
+                 INSERT INTO child_deferred VALUES (NEW.id + 30000, NEW.pid, NEW.y);
+                END",
+            ];
+
+            // Randomly select up to 2 triggers from the list
+            let num_triggers = rng.random_range(1..=2);
+            let mut selected_indices = std::collections::HashSet::new();
+            while selected_indices.len() < num_triggers {
+                selected_indices.insert(rng.random_range(0..trigger_definitions.len()));
+            }
+
+            // Create the selected triggers
+            for &idx in selected_indices.iter() {
+                let s = log_and_exec(trigger_definitions[idx]);
+                limbo_exec_rows(&limbo_db, &limbo, &s);
+                sqlite.execute(&s, params![]).unwrap();
+            }
+
             // Transaction-based mutations with mix of deferred and immediate operations
             let mut in_tx = false;
             for tx_num in 0..INNER_ITERS {
@@ -1856,16 +1954,128 @@ mod fuzz_tests {
             }
         }
     }
-
     #[test]
     /// Create a table with a random number of columns and indexes, and then randomly update or delete rows from the table.
     /// Verify that the results are the same for SQLite and Turso.
     pub fn table_index_mutation_fuzz() {
+        /// Format a nice diff between two result sets for better error messages
+        #[allow(clippy::too_many_arguments)]
+        fn format_rows_diff(
+            sqlite_rows: &[Vec<Value>],
+            limbo_rows: &[Vec<Value>],
+            seed: u64,
+            query: &str,
+            table_def: &str,
+            indexes: &[String],
+            trigger: Option<&String>,
+            dml_statements: &[String],
+        ) -> String {
+            let mut diff = String::new();
+            let sqlite_rows_len = sqlite_rows.len();
+            let limbo_rows_len = limbo_rows.len();
+            diff.push_str(&format!(
+            "\n\n=== Row Count Difference ===\nSQLite: {sqlite_rows_len} rows, Limbo: {limbo_rows_len} rows\n",
+        ));
+
+            // Find rows that differ at the same index
+            let max_len = sqlite_rows.len().max(limbo_rows.len());
+            let mut diff_indices = Vec::new();
+            for i in 0..max_len {
+                let sqlite_row = sqlite_rows.get(i);
+                let limbo_row = limbo_rows.get(i);
+                if sqlite_row != limbo_row {
+                    diff_indices.push(i);
+                }
+            }
+
+            if !diff_indices.is_empty() {
+                diff.push_str("\n=== Rows Differing at Same Index (showing first 10) ===\n");
+                for &idx in diff_indices.iter().take(10) {
+                    diff.push_str(&format!("\nIndex {idx}:\n"));
+                    if let Some(sqlite_row) = sqlite_rows.get(idx) {
+                        diff.push_str(&format!("  SQLite: {sqlite_row:?}\n"));
+                    } else {
+                        diff.push_str("  SQLite: <missing>\n");
+                    }
+                    if let Some(limbo_row) = limbo_rows.get(idx) {
+                        diff.push_str(&format!("  Limbo:  {limbo_row:?}\n"));
+                    } else {
+                        diff.push_str("  Limbo:  <missing>\n");
+                    }
+                }
+                if diff_indices.len() > 10 {
+                    diff.push_str(&format!(
+                        "\n... and {} more differences\n",
+                        diff_indices.len() - 10
+                    ));
+                }
+            }
+
+            // Find rows that are in one but not the other (using linear search since Value doesn't implement Hash)
+            let mut only_in_sqlite = Vec::new();
+            for sqlite_row in sqlite_rows.iter() {
+                if !limbo_rows.iter().any(|limbo_row| limbo_row == sqlite_row) {
+                    only_in_sqlite.push(sqlite_row);
+                }
+            }
+
+            let mut only_in_limbo = Vec::new();
+            for limbo_row in limbo_rows.iter() {
+                if !sqlite_rows.iter().any(|sqlite_row| sqlite_row == limbo_row) {
+                    only_in_limbo.push(limbo_row);
+                }
+            }
+
+            if !only_in_sqlite.is_empty() {
+                diff.push_str("\n=== Rows Only in SQLite (showing first 10) ===\n");
+                for row in only_in_sqlite.iter().take(10) {
+                    diff.push_str(&format!("  {row:?}\n"));
+                }
+                if only_in_sqlite.len() > 10 {
+                    diff.push_str(&format!(
+                        "\n... and {} more rows\n",
+                        only_in_sqlite.len() - 10
+                    ));
+                }
+            }
+
+            if !only_in_limbo.is_empty() {
+                diff.push_str("\n=== Rows Only in Limbo (showing first 10) ===\n");
+                for row in only_in_limbo.iter().take(10) {
+                    diff.push_str(&format!("  {row:?}\n"));
+                }
+                if only_in_limbo.len() > 10 {
+                    diff.push_str(&format!(
+                        "\n... and {} more rows\n",
+                        only_in_limbo.len() - 10
+                    ));
+                }
+            }
+
+            diff.push_str(&format!(
+                "\n=== Context ===\nSeed: {seed}\nQuery: {query}\n",
+            ));
+
+            diff.push_str("\n=== DDL/DML to Reproduce ===\n");
+            diff.push_str(&format!("{table_def};\n"));
+            for idx in indexes.iter() {
+                diff.push_str(&format!("{idx};\n"));
+            }
+            if let Some(trigger) = trigger {
+                diff.push_str(&format!("{trigger};\n"));
+            }
+            for dml in dml_statements.iter() {
+                diff.push_str(&format!("{dml};\n"));
+            }
+
+            diff
+        }
+
         let _ = env_logger::try_init();
         let (mut rng, seed) = rng_from_time_or_env();
         println!("table_index_mutation_fuzz seed: {seed}");
 
-        const OUTER_ITERATIONS: usize = 100;
+        const OUTER_ITERATIONS: usize = 30;
         for i in 0..OUTER_ITERATIONS {
             println!(
                 "table_index_mutation_fuzz iteration {}/{}",
@@ -1926,8 +2136,16 @@ mod fuzz_tests {
                 sqlite_conn.execute(t, params![]).unwrap();
             }
 
+            let use_trigger = rng.random_bool(1.0);
+
             // Generate initial data
-            let num_inserts = rng.random_range(10..=1000);
+            // Triggers can cause quadratic complexity to the tested operations so limit total row count
+            // whenever we have one to make the test runtime reasonable.
+            let num_inserts = if use_trigger {
+                rng.random_range(10..=100)
+            } else {
+                rng.random_range(10..=1000)
+            };
             let mut tuples = HashSet::new();
             while tuples.len() < num_inserts {
                 tuples.insert(
@@ -1953,13 +2171,15 @@ mod fuzz_tests {
                 .map(|i| format!("c{i}"))
                 .collect::<Vec<_>>()
                 .join(", ");
+            let insert_type = match rng.random_range(0..3) {
+                0 => "",
+                1 => "OR REPLACE",
+                2 => "OR IGNORE",
+                _ => unreachable!(),
+            };
             let insert = format!(
                 "INSERT {} INTO t ({}) VALUES {}",
-                if rng.random_bool(0.4) {
-                    "OR IGNORE"
-                } else {
-                    ""
-                },
+                insert_type,
                 col_names,
                 insert_values.join(", ")
             );
@@ -1969,6 +2189,145 @@ mod fuzz_tests {
             sqlite_conn.execute(&insert, params![]).unwrap();
             limbo_exec_rows(&limbo_db, &limbo_conn, &insert);
 
+            // Self-affecting triggers (e.g CREATE TRIGGER t BEFORE DELETE ON t BEGIN UPDATE t ... END) are
+            // an easy source of bugs, so create one some of the time.
+            let trigger = if use_trigger {
+                // Create a random trigger
+                let trigger_time = if rng.random_bool(0.5) {
+                    "BEFORE"
+                } else {
+                    "AFTER"
+                };
+                let trigger_event = match rng.random_range(0..3) {
+                    0 => "INSERT".to_string(),
+                    1 => {
+                        // Optionally specify columns for UPDATE trigger
+                        if rng.random_bool(0.5) {
+                            let update_col = rng.random_range(0..num_cols);
+                            format!("UPDATE OF c{update_col}")
+                        } else {
+                            "UPDATE".to_string()
+                        }
+                    }
+                    2 => "DELETE".to_string(),
+                    _ => unreachable!(),
+                };
+
+                // Determine if OLD/NEW references are available based on trigger event
+                let has_old =
+                    trigger_event.starts_with("UPDATE") || trigger_event.starts_with("DELETE");
+                let has_new =
+                    trigger_event.starts_with("UPDATE") || trigger_event.starts_with("INSERT");
+
+                // Generate trigger action (INSERT, UPDATE, or DELETE)
+                let trigger_action = match rng.random_range(0..3) {
+                    0 => {
+                        // INSERT action
+                        let values = (0..num_cols)
+                            .map(|i| {
+                                // Randomly use OLD/NEW values if available
+                                if has_old && rng.random_bool(0.3) {
+                                    format!("OLD.c{i}")
+                                } else if has_new && rng.random_bool(0.3) {
+                                    format!("NEW.c{i}")
+                                } else {
+                                    rng.random_range(0..1000).to_string()
+                                }
+                            })
+                            .collect::<Vec<_>>()
+                            .join(", ");
+                        let insert_conflict_action = match rng.random_range(0..3) {
+                            0 => "",
+                            1 => " OR REPLACE",
+                            2 => " OR IGNORE",
+                            _ => unreachable!(),
+                        };
+                        format!(
+                            "INSERT{insert_conflict_action} INTO t ({col_names}) VALUES ({values})"
+                        )
+                    }
+                    1 => {
+                        // UPDATE action
+                        let update_col = rng.random_range(0..num_cols);
+                        let new_value = if has_old && rng.random_bool(0.3) {
+                            let ref_col = rng.random_range(0..num_cols);
+                            // Sometimes make it a function of the OLD column
+                            if rng.random_bool(0.5) {
+                                let operator = *["+", "-", "*"].choose(&mut rng).unwrap();
+                                let amount = rng.random_range(1..100);
+                                format!("OLD.c{ref_col} {operator} {amount}")
+                            } else {
+                                format!("OLD.c{ref_col}")
+                            }
+                        } else if has_new && rng.random_bool(0.3) {
+                            let ref_col = rng.random_range(0..num_cols);
+                            // Sometimes make it a function of the NEW column
+                            if rng.random_bool(0.5) {
+                                let operator = *["+", "-", "*"].choose(&mut rng).unwrap();
+                                let amount = rng.random_range(1..100);
+                                format!("NEW.c{ref_col} {operator} {amount}")
+                            } else {
+                                format!("NEW.c{ref_col}")
+                            }
+                        } else {
+                            rng.random_range(0..1000).to_string()
+                        };
+                        let op = match rng.random_range(0..=3) {
+                            0 => "<",
+                            1 => "<=",
+                            2 => ">",
+                            3 => ">=",
+                            _ => unreachable!(),
+                        };
+                        let threshold = if has_old && rng.random_bool(0.3) {
+                            let ref_col = rng.random_range(0..num_cols);
+                            format!("OLD.c{ref_col}")
+                        } else if has_new && rng.random_bool(0.3) {
+                            let ref_col = rng.random_range(0..num_cols);
+                            format!("NEW.c{ref_col}")
+                        } else {
+                            rng.random_range(0..1000).to_string()
+                        };
+                        format!("UPDATE t SET c{update_col} = {new_value} WHERE c{update_col} {op} {threshold}")
+                    }
+                    2 => {
+                        // DELETE action
+                        let delete_col = rng.random_range(0..num_cols);
+                        let op = match rng.random_range(0..=3) {
+                            0 => "<",
+                            1 => "<=",
+                            2 => ">",
+                            3 => ">=",
+                            _ => unreachable!(),
+                        };
+                        let threshold = if has_old && rng.random_bool(0.3) {
+                            let ref_col = rng.random_range(0..num_cols);
+                            format!("OLD.c{ref_col}")
+                        } else if has_new && rng.random_bool(0.3) {
+                            let ref_col = rng.random_range(0..num_cols);
+                            format!("NEW.c{ref_col}")
+                        } else {
+                            rng.random_range(0..1000).to_string()
+                        };
+                        format!("DELETE FROM t WHERE c{delete_col} {op} {threshold}")
+                    }
+                    _ => unreachable!(),
+                };
+
+                let create_trigger = format!(
+                    "CREATE TRIGGER test_trigger {trigger_time} {trigger_event} ON t BEGIN {trigger_action}; END;",
+                );
+
+                sqlite_conn.execute(&create_trigger, params![]).unwrap();
+                limbo_exec_rows(&limbo_db, &limbo_conn, &create_trigger);
+                Some(create_trigger)
+            } else {
+                None
+            };
+            if let Some(ref trigger) = trigger {
+                println!("{trigger};");
+            }
+
             const COMPARISONS: [&str; 3] = ["=", "<", ">"];
             const INNER_ITERATIONS: usize = 20;
 
@@ -1976,7 +2335,6 @@ mod fuzz_tests {
                 let do_update = rng.random_range(0..2) == 0;
 
                 let comparison = COMPARISONS[rng.random_range(0..COMPARISONS.len())];
-                let affected_col = rng.random_range(0..num_cols);
                 let predicate_col = rng.random_range(0..num_cols);
                 let predicate_value = rng.random_range(0..1000);
 
@@ -2000,6 +2358,7 @@ mod fuzz_tests {
                 };
 
                 let query = if do_update {
+                    let affected_col = rng.random_range(0..num_cols);
                     let num_updates = rng.random_range(1..=num_cols);
                     let mut values = Vec::new();
                     for _ in 0..num_updates {
@@ -2048,10 +2407,19 @@ mod fuzz_tests {
                 let sqlite_rows = sqlite_exec_rows(&sqlite_conn, &verify_query);
                 let limbo_rows = limbo_exec_rows(&limbo_db, &limbo_conn, &verify_query);
 
-                assert_eq!(
-                    sqlite_rows, limbo_rows,
-                    "Different results after mutation! limbo: {limbo_rows:?}, sqlite: {sqlite_rows:?}, seed: {seed}, query: {query}",
+                if sqlite_rows != limbo_rows {
+                    let diff_msg = format_rows_diff(
+                        &sqlite_rows,
+                        &limbo_rows,
+                        seed,
+                        &query,
+                        &table_def,
+                        &indexes,
+                        trigger.as_ref(),
+                        &dml_statements,
                     );
+                    panic!("Different results after mutation!{diff_msg}");
+                }
 
                 // Run integrity check on limbo db using rusqlite
                 if let Err(e) = rusqlite_integrity_check(&limbo_db.path) {
@@ -2059,6 +2427,9 @@ mod fuzz_tests {
                     for t in indexes.iter() {
                         println!("{t};");
                     }
+                    if let Some(trigger) = trigger {
+                        println!("{trigger};");
+                    }
                     for t in dml_statements.iter() {
                         println!("{t};");
                     }

tests/integration/mod.rs

@@ -5,6 +5,7 @@ mod index_method;
 mod pragma;
 mod query_processing;
 mod storage;
+mod trigger;
 mod wal;
 
 #[cfg(test)]

tests/integration/trigger.rs

@@ -0,0 +1,888 @@
+use crate::common::TempDatabase;
+
+#[test]
+fn test_create_trigger() {
+    let _ = tracing_subscriber::fmt()
+        .with_env_filter(tracing_subscriber::EnvFilter::from_default_env())
+        .try_init();
+
+    let db = TempDatabase::new_empty();
+    let conn = db.connect_limbo();
+
+    conn.execute("CREATE TABLE test (x, y TEXT)").unwrap();
+
+    conn.execute(
+        "CREATE TRIGGER t1 BEFORE INSERT ON test BEGIN
+         INSERT INTO test VALUES (100, 'triggered');
+        END",
+    )
+    .unwrap();
+
+    conn.execute("INSERT INTO test VALUES (1, 'hello')")
+        .unwrap();
+
+    let mut stmt = conn.prepare("SELECT * FROM test ORDER BY rowid").unwrap();
+    let mut results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                results.push((
+                    row.get_value(0).as_int().unwrap(),
+                    row.get_value(1).cast_text().unwrap().to_string(),
+                ));
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+
+    // Row inserted by trigger goes first
+    assert_eq!(results[0], (100, "triggered".to_string()));
+    assert_eq!(results[1], (1, "hello".to_string()));
+}
+
+#[test]
+fn test_drop_trigger() {
+    let db = TempDatabase::new_empty();
+    let conn = db.connect_limbo();
+
+    conn.execute("CREATE TABLE test (x INTEGER PRIMARY KEY)")
+        .unwrap();
+
+    conn.execute("CREATE TRIGGER t1 BEFORE INSERT ON test BEGIN SELECT 1; END")
+        .unwrap();
+
+    // Verify trigger exists
+    let mut stmt = conn
+        .prepare("SELECT name FROM sqlite_schema WHERE type='trigger' AND name='t1'")
+        .unwrap();
+    let mut results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                results.push(row.get_value(0).cast_text().unwrap().to_string());
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+    assert_eq!(results.len(), 1);
+
+    conn.execute("DROP TRIGGER t1").unwrap();
+
+    // Verify trigger is gone
+    let mut stmt = conn
+        .prepare("SELECT name FROM sqlite_schema WHERE type='trigger' AND name='t1'")
+        .unwrap();
+    let mut results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                results.push(row.get_value(0).cast_text().unwrap().to_string());
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+    assert_eq!(results.len(), 0);
+}
+
+#[test]
+fn test_trigger_after_insert() {
+    let db = TempDatabase::new_empty();
+    let conn = db.connect_limbo();
+
+    conn.execute("CREATE TABLE test (x INTEGER PRIMARY KEY, y TEXT)")
+        .unwrap();
+    conn.execute("CREATE TABLE log (x INTEGER, y TEXT)")
+        .unwrap();
+
+    conn.execute(
+        "CREATE TRIGGER t1 AFTER INSERT ON test BEGIN
+         INSERT INTO log VALUES (NEW.x, NEW.y);
+        END",
+    )
+    .unwrap();
+
+    conn.execute("INSERT INTO test VALUES (1, 'hello')")
+        .unwrap();
+
+    let mut stmt = conn.prepare("SELECT * FROM log").unwrap();
+    let mut results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                results.push((
+                    row.get_value(0).as_int().unwrap(),
+                    row.get_value(1).cast_text().unwrap().to_string(),
+                ));
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+
+    assert_eq!(results.len(), 1);
+    assert_eq!(results[0], (1, "hello".to_string()));
+}
+
+#[test]
+fn test_trigger_when_clause() {
+    let db = TempDatabase::new_empty();
+    let conn = db.connect_limbo();
+
+    conn.execute("CREATE TABLE test (x INTEGER PRIMARY KEY, y INTEGER)")
+        .unwrap();
+    conn.execute("CREATE TABLE log (x INTEGER)").unwrap();
+
+    conn.execute(
+        "CREATE TRIGGER t1 AFTER INSERT ON test WHEN NEW.y > 10 BEGIN
+         INSERT INTO log VALUES (NEW.x);
+        END",
+    )
+    .unwrap();
+
+    conn.execute("INSERT INTO test VALUES (1, 5)").unwrap();
+    conn.execute("INSERT INTO test VALUES (2, 15)").unwrap();
+
+    let mut stmt = conn.prepare("SELECT * FROM log").unwrap();
+    let mut results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                results.push(row.get_value(0).as_int().unwrap());
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+
+    assert_eq!(results.len(), 1);
+    assert_eq!(results[0], 2);
+}
+
+#[test]
+fn test_trigger_drop_table_drops_triggers() {
+    let db = TempDatabase::new_empty();
+    let conn = db.connect_limbo();
+
+    conn.execute("CREATE TABLE test (x INTEGER PRIMARY KEY)")
+        .unwrap();
+    conn.execute("CREATE TRIGGER t1 BEFORE INSERT ON test BEGIN SELECT 1; END")
+        .unwrap();
+
+    // Verify trigger exists
+    let mut stmt = conn
+        .prepare("SELECT name FROM sqlite_schema WHERE type='trigger' AND name='t1'")
+        .unwrap();
+    let mut results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                results.push(row.get_value(0).cast_text().unwrap().to_string());
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+    assert_eq!(results.len(), 1);
+
+    conn.execute("DROP TABLE test").unwrap();
+
+    // Verify trigger is gone
+    let mut stmt = conn
+        .prepare("SELECT name FROM sqlite_schema WHERE type='trigger' AND name='t1'")
+        .unwrap();
+    let mut results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                results.push(row.get_value(0).cast_text().unwrap().to_string());
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+    assert_eq!(results.len(), 0);
+}
+
+#[test]
+fn test_trigger_new_old_references() {
+    let db = TempDatabase::new_empty();
+    let conn = db.connect_limbo();
+
+    conn.execute("CREATE TABLE test (x INTEGER PRIMARY KEY, y TEXT)")
+        .unwrap();
+    conn.execute("CREATE TABLE log (msg TEXT)").unwrap();
+
+    conn.execute("INSERT INTO test VALUES (1, 'hello')")
+        .unwrap();
+
+    conn.execute(
+        "CREATE TRIGGER t1 AFTER UPDATE ON test BEGIN
+         INSERT INTO log VALUES ('old=' || OLD.y || ' new=' || NEW.y);
+        END",
+    )
+    .unwrap();
+
+    conn.execute("UPDATE test SET y = 'world' WHERE x = 1")
+        .unwrap();
+
+    let mut stmt = conn.prepare("SELECT * FROM log").unwrap();
+    let mut results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                results.push(row.get_value(0).cast_text().unwrap().to_string());
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+
+    assert_eq!(results.len(), 1);
+    assert_eq!(results[0], "old=hello new=world");
+}
+
+#[test]
+fn test_multiple_triggers_same_event() {
+    let db = TempDatabase::new_empty();
+    let conn = db.connect_limbo();
+
+    conn.execute("CREATE TABLE test (x INTEGER PRIMARY KEY)")
+        .unwrap();
+    conn.execute("CREATE TABLE log (msg TEXT)").unwrap();
+
+    conn.execute(
+        "CREATE TRIGGER t1 BEFORE INSERT ON test BEGIN
+         INSERT INTO log VALUES ('trigger1');
+        END",
+    )
+    .unwrap();
+
+    conn.execute(
+        "CREATE TRIGGER t2 BEFORE INSERT ON test BEGIN
+         INSERT INTO log VALUES ('trigger2');
+        END",
+    )
+    .unwrap();
+
+    conn.execute("INSERT INTO test VALUES (1)").unwrap();
+
+    let mut stmt = conn.prepare("SELECT * FROM log ORDER BY msg").unwrap();
+    let mut results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                results.push(row.get_value(0).cast_text().unwrap().to_string());
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+
+    assert_eq!(results.len(), 2);
+    assert_eq!(results[0], "trigger1");
+    assert_eq!(results[1], "trigger2");
+}
+
+#[test]
+fn test_two_triggers_on_same_table() {
+    let db = TempDatabase::new_empty();
+    let conn = db.connect_limbo();
+
+    conn.execute("CREATE TABLE test (x, msg TEXT)").unwrap();
+    conn.execute("CREATE TABLE log (msg TEXT)").unwrap();
+
+    // Trigger A: fires on INSERT to test, inserts into log and test (which would trigger B)
+    conn.execute(
+        "CREATE TRIGGER trigger_a AFTER INSERT ON test BEGIN
+         INSERT INTO log VALUES ('trigger_a fired for x=' || NEW.x);
+         INSERT INTO test VALUES (NEW.x + 100, 'from_a');
+        END",
+    )
+    .unwrap();
+
+    // Trigger B: fires on INSERT to test, inserts into log and test (which would trigger A)
+    conn.execute(
+        "CREATE TRIGGER trigger_b AFTER INSERT ON test BEGIN
+         INSERT INTO log VALUES ('trigger_b fired for x=' || NEW.x);
+         INSERT INTO test VALUES (NEW.x + 200, 'from_b');
+        END",
+    )
+    .unwrap();
+
+    // Insert initial row - this should trigger A, which triggers B, which tries to trigger A again (prevented)
+    conn.execute("INSERT INTO test VALUES (1, 'initial')")
+        .unwrap();
+
+    // Check log entries to verify recursion was prevented
+    let mut stmt = conn.prepare("SELECT * FROM log ORDER BY rowid").unwrap();
+    let mut results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                results.push(row.get_value(0).cast_text().unwrap().to_string());
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+
+    // At minimum, we should see both triggers fire and not infinite loop
+    assert!(
+        results.len() >= 2,
+        "Expected at least 2 log entries, got {}",
+        results.len()
+    );
+    assert!(
+        results.iter().any(|s| s.contains("trigger_a")),
+        "trigger_a should have fired"
+    );
+    assert!(
+        results.iter().any(|s| s.contains("trigger_b")),
+        "trigger_b should have fired"
+    );
+}
+
+#[test]
+fn test_trigger_mutual_recursion() {
+    let db = TempDatabase::new_empty();
+    let conn = db.connect_limbo();
+
+    conn.execute("CREATE TABLE t (id INTEGER, msg TEXT)")
+        .unwrap();
+    conn.execute("CREATE TABLE u (id INTEGER, msg TEXT)")
+        .unwrap();
+
+    // Trigger on T: fires on INSERT to t, inserts into u
+    conn.execute(
+        "CREATE TRIGGER trigger_on_t AFTER INSERT ON t BEGIN
+         INSERT INTO u VALUES (NEW.id + 1000, 'from_t');
+        END",
+    )
+    .unwrap();
+
+    // Trigger on U: fires on INSERT to u, inserts into t
+    conn.execute(
+        "CREATE TRIGGER trigger_on_u AFTER INSERT ON u BEGIN
+         INSERT INTO t VALUES (NEW.id + 2000, 'from_u');
+        END",
+    )
+    .unwrap();
+
+    // Insert initial row into t - this should trigger the chain
+    conn.execute("INSERT INTO t VALUES (1, 'initial')").unwrap();
+
+    // Check that both tables have entries
+    let mut stmt = conn.prepare("SELECT * FROM t ORDER BY rowid").unwrap();
+    let mut t_results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                t_results.push((
+                    row.get_value(0).as_int().unwrap(),
+                    row.get_value(1).cast_text().unwrap().to_string(),
+                ));
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+
+    let mut stmt = conn.prepare("SELECT * FROM u ORDER BY rowid").unwrap();
+    let mut u_results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                u_results.push((
+                    row.get_value(0).as_int().unwrap(),
+                    row.get_value(1).cast_text().unwrap().to_string(),
+                ));
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+
+    // Verify the chain executed without infinite recursion
+    assert!(!t_results.is_empty(), "Expected at least 1 entry in t");
+    assert!(!u_results.is_empty(), "Expected at least 1 entry in u");
+
+    // Verify initial insert
+    assert_eq!(t_results[0], (1, "initial".to_string()));
+
+    // Verify trigger on t fired (inserted into u)
+    assert_eq!(u_results[0], (1001, "from_t".to_string()));
+}
+
+#[test]
+fn test_after_insert_trigger() {
+    let db = TempDatabase::new_empty();
+    let conn = db.connect_limbo();
+
+    // Create table and log table
+    conn.execute("CREATE TABLE items (id INTEGER PRIMARY KEY, name TEXT)")
+        .unwrap();
+    conn.execute("CREATE TABLE audit_log (action TEXT, item_id INTEGER, item_name TEXT)")
+        .unwrap();
+
+    // Create AFTER INSERT trigger
+    conn.execute(
+        "CREATE TRIGGER after_insert_items
+         AFTER INSERT ON items
+         BEGIN
+             INSERT INTO audit_log VALUES ('INSERT', NEW.id, NEW.name);
+         END",
+    )
+    .unwrap();
+
+    // Insert data
+    conn.execute("INSERT INTO items VALUES (1, 'apple')")
+        .unwrap();
+    conn.execute("INSERT INTO items VALUES (2, 'banana')")
+        .unwrap();
+
+    // Verify audit log
+    let mut stmt = conn
+        .prepare("SELECT * FROM audit_log ORDER BY rowid")
+        .unwrap();
+    let mut results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                results.push((
+                    row.get_value(0).cast_text().unwrap().to_string(),
+                    row.get_value(1).as_int().unwrap(),
+                    row.get_value(2).cast_text().unwrap().to_string(),
+                ));
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+
+    assert_eq!(results.len(), 2);
+    assert_eq!(results[0], ("INSERT".to_string(), 1, "apple".to_string()));
+    assert_eq!(results[1], ("INSERT".to_string(), 2, "banana".to_string()));
+}
+
+#[test]
+fn test_before_update_of_trigger() {
+    let db = TempDatabase::new_empty();
+    let conn = db.connect_limbo();
+
+    // Create table with multiple columns
+    conn.execute("CREATE TABLE products (id INTEGER PRIMARY KEY, name TEXT, price INTEGER)")
+        .unwrap();
+    conn.execute(
+        "CREATE TABLE price_history (product_id INTEGER, old_price INTEGER, new_price INTEGER)",
+    )
+    .unwrap();
+
+    // Create BEFORE UPDATE OF trigger - only fires when price column is updated
+    conn.execute(
+        "CREATE TRIGGER before_update_price
+         BEFORE UPDATE OF price ON products
+         BEGIN
+             INSERT INTO price_history VALUES (OLD.id, OLD.price, NEW.price);
+         END",
+    )
+    .unwrap();
+
+    // Insert initial data
+    conn.execute("INSERT INTO products VALUES (1, 'widget', 100)")
+        .unwrap();
+    conn.execute("INSERT INTO products VALUES (2, 'gadget', 200)")
+        .unwrap();
+
+    // Update price - should fire trigger
+    conn.execute("UPDATE products SET price = 150 WHERE id = 1")
+        .unwrap();
+
+    // Update name only - should NOT fire trigger
+    conn.execute("UPDATE products SET name = 'super widget' WHERE id = 1")
+        .unwrap();
+
+    // Update both name and price - should fire trigger
+    conn.execute("UPDATE products SET name = 'mega gadget', price = 250 WHERE id = 2")
+        .unwrap();
+
+    // Verify price history
+    let mut stmt = conn
+        .prepare("SELECT * FROM price_history ORDER BY rowid")
+        .unwrap();
+    let mut results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                results.push((
+                    row.get_value(0).as_int().unwrap(),
+                    row.get_value(1).as_int().unwrap(),
+                    row.get_value(2).as_int().unwrap(),
+                ));
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+
+    // Should have 2 entries (not 3, because name-only update didn't fire)
+    assert_eq!(results.len(), 2);
+    assert_eq!(results[0], (1, 100, 150));
+    assert_eq!(results[1], (2, 200, 250));
+}
+
+#[test]
+fn test_after_update_of_trigger() {
+    let db = TempDatabase::new_empty();
+    let conn = db.connect_limbo();
+
+    // Create table
+    conn.execute("CREATE TABLE employees (id INTEGER PRIMARY KEY, name TEXT, salary INTEGER)")
+        .unwrap();
+    conn.execute("CREATE TABLE salary_changes (emp_id INTEGER, old_salary INTEGER, new_salary INTEGER, change_amount INTEGER)")
+        .unwrap();
+
+    // Create AFTER UPDATE OF trigger with multiple statements
+    conn.execute(
+        "CREATE TRIGGER after_update_salary
+         AFTER UPDATE OF salary ON employees
+         BEGIN
+             INSERT INTO salary_changes VALUES (NEW.id, OLD.salary, NEW.salary, NEW.salary - OLD.salary);
+         END",
+    )
+    .unwrap();
+
+    // Insert initial data
+    conn.execute("INSERT INTO employees VALUES (1, 'Alice', 50000)")
+        .unwrap();
+    conn.execute("INSERT INTO employees VALUES (2, 'Bob', 60000)")
+        .unwrap();
+
+    // Update salary
+    conn.execute("UPDATE employees SET salary = 55000 WHERE id = 1")
+        .unwrap();
+    conn.execute("UPDATE employees SET salary = 65000 WHERE id = 2")
+        .unwrap();
+
+    // Verify salary changes
+    let mut stmt = conn
+        .prepare("SELECT * FROM salary_changes ORDER BY rowid")
+        .unwrap();
+    let mut results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                results.push((
+                    row.get_value(0).as_int().unwrap(),
+                    row.get_value(1).as_int().unwrap(),
+                    row.get_value(2).as_int().unwrap(),
+                    row.get_value(3).as_int().unwrap(),
+                ));
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+
+    assert_eq!(results.len(), 2);
+    assert_eq!(results[0], (1, 50000, 55000, 5000));
+    assert_eq!(results[1], (2, 60000, 65000, 5000));
+}
+
+fn log(s: &str) -> &str {
+    tracing::info!("{}", s);
+    s
+}
+
+#[test]
+fn test_before_delete_trigger() {
+    let db = TempDatabase::new_empty();
+    let conn = db.connect_limbo();
+
+    // Create tables
+    conn.execute(log(
+        "CREATE TABLE users (id INTEGER PRIMARY KEY, username TEXT)",
+    ))
+    .unwrap();
+    conn.execute(log(
+        "CREATE TABLE deleted_users (id INTEGER, username TEXT, deleted_at INTEGER)",
+    ))
+    .unwrap();
+
+    // Create BEFORE DELETE trigger
+    conn.execute(log("CREATE TRIGGER before_delete_users
+         BEFORE DELETE ON users
+         BEGIN
+             INSERT INTO deleted_users VALUES (OLD.id, OLD.username, 12345);
+         END"))
+        .unwrap();
+
+    // Insert data
+    conn.execute(log("INSERT INTO users VALUES (1, 'alice')"))
+        .unwrap();
+    conn.execute(log("INSERT INTO users VALUES (2, 'bob')"))
+        .unwrap();
+    conn.execute(log("INSERT INTO users VALUES (3, 'charlie')"))
+        .unwrap();
+
+    // Delete some users
+    conn.execute(log("DELETE FROM users WHERE id = 2")).unwrap();
+    conn.execute(log("DELETE FROM users WHERE id = 3")).unwrap();
+
+    // Verify deleted_users table
+    let mut stmt = conn
+        .prepare(log("SELECT * FROM deleted_users ORDER BY id"))
+        .unwrap();
+    let mut results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                results.push((
+                    row.get_value(0).as_int().unwrap(),
+                    row.get_value(1).cast_text().unwrap().to_string(),
+                    row.get_value(2).as_int().unwrap(),
+                ));
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+
+    assert_eq!(results.len(), 2);
+    assert_eq!(results[0], (2, "bob".to_string(), 12345));
+    assert_eq!(results[1], (3, "charlie".to_string(), 12345));
+
+    // Verify remaining users
+    let mut stmt = conn.prepare(log("SELECT COUNT(*) FROM users")).unwrap();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                assert_eq!(row.get_value(0).as_int().unwrap(), 1);
+                break;
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+}
+
+#[test]
+fn test_after_delete_trigger() {
+    let db = TempDatabase::new_empty();
+    let conn = db.connect_limbo();
+
+    // Create tables
+    conn.execute(
+        "CREATE TABLE orders (id INTEGER PRIMARY KEY, customer_id INTEGER, amount INTEGER)",
+    )
+    .unwrap();
+    conn.execute(
+        "CREATE TABLE order_archive (order_id INTEGER, customer_id INTEGER, amount INTEGER)",
+    )
+    .unwrap();
+
+    // Create AFTER DELETE trigger
+    conn.execute(
+        "CREATE TRIGGER after_delete_orders
+         AFTER DELETE ON orders
+         BEGIN
+             INSERT INTO order_archive VALUES (OLD.id, OLD.customer_id, OLD.amount);
+         END",
+    )
+    .unwrap();
+
+    // Insert data
+    conn.execute("INSERT INTO orders VALUES (1, 100, 50)")
+        .unwrap();
+    conn.execute("INSERT INTO orders VALUES (2, 101, 75)")
+        .unwrap();
+    conn.execute("INSERT INTO orders VALUES (3, 100, 100)")
+        .unwrap();
+
+    // Delete orders
+    conn.execute("DELETE FROM orders WHERE customer_id = 100")
+        .unwrap();
+
+    // Verify archive
+    let mut stmt = conn
+        .prepare("SELECT * FROM order_archive ORDER BY order_id")
+        .unwrap();
+    let mut results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                results.push((
+                    row.get_value(0).as_int().unwrap(),
+                    row.get_value(1).as_int().unwrap(),
+                    row.get_value(2).as_int().unwrap(),
+                ));
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+
+    assert_eq!(results.len(), 2);
+    assert_eq!(results[0], (1, 100, 50));
+    assert_eq!(results[1], (3, 100, 100));
+}
+
+#[test]
+fn test_trigger_with_multiple_statements() {
+    let db = TempDatabase::new_empty();
+    let conn = db.connect_limbo();
+
+    // Create tables
+    conn.execute("CREATE TABLE accounts (id INTEGER PRIMARY KEY, balance INTEGER)")
+        .unwrap();
+    conn.execute(
+        "CREATE TABLE transactions (account_id INTEGER, old_balance INTEGER, new_balance INTEGER)",
+    )
+    .unwrap();
+    conn.execute("CREATE TABLE audit (message TEXT)").unwrap();
+
+    // Create trigger with multiple statements
+    conn.execute(
+        "CREATE TRIGGER track_balance_changes
+         AFTER UPDATE OF balance ON accounts
+         BEGIN
+             INSERT INTO transactions VALUES (NEW.id, OLD.balance, NEW.balance);
+             INSERT INTO audit VALUES ('Balance changed for account ' || NEW.id);
+         END",
+    )
+    .unwrap();
+
+    // Insert initial data
+    conn.execute("INSERT INTO accounts VALUES (1, 1000)")
+        .unwrap();
+    conn.execute("INSERT INTO accounts VALUES (2, 2000)")
+        .unwrap();
+
+    // Update balances
+    conn.execute("UPDATE accounts SET balance = 1500 WHERE id = 1")
+        .unwrap();
+    conn.execute("UPDATE accounts SET balance = 2500 WHERE id = 2")
+        .unwrap();
+
+    // Verify transactions table
+    let mut stmt = conn
+        .prepare("SELECT * FROM transactions ORDER BY rowid")
+        .unwrap();
+    let mut trans_results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                trans_results.push((
+                    row.get_value(0).as_int().unwrap(),
+                    row.get_value(1).as_int().unwrap(),
+                    row.get_value(2).as_int().unwrap(),
+                ));
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+
+    assert_eq!(trans_results.len(), 2);
+    assert_eq!(trans_results[0], (1, 1000, 1500));
+    assert_eq!(trans_results[1], (2, 2000, 2500));
+
+    // Verify audit table
+    let mut stmt = conn.prepare("SELECT * FROM audit ORDER BY rowid").unwrap();
+    let mut audit_results = Vec::new();
+    loop {
+        match stmt.step().unwrap() {
+            turso_core::StepResult::Row => {
+                let row = stmt.row().unwrap();
+                audit_results.push(row.get_value(0).cast_text().unwrap().to_string());
+            }
+            turso_core::StepResult::Done => break,
+            turso_core::StepResult::IO => {
+                stmt.run_once().unwrap();
+            }
+            _ => panic!("Unexpected step result"),
+        }
+    }
+
+    assert_eq!(audit_results.len(), 2);
+    assert_eq!(audit_results[0], "Balance changed for account 1");
+    assert_eq!(audit_results[1], "Balance changed for account 2");
+}