modify translate_select to return number of result columns

core/translate/insert.rs

@@ -99,6 +99,15 @@ pub fn translate_insert(
         })
         .collect::<Vec<(&String, usize, usize)>>();
     let root_page = btree_table.root_page;
+
+    let inserting_multiple_rows = match body {
+        InsertBody::Select(select, _) => match select.body.select.as_ref() {
+            OneSelect::Values(values) => values.len() > 1,
+            OneSelect::Select(..) => true,
+        },
+        InsertBody::DefaultValues => false,
+    };
+
     let values = match body {
         InsertBody::Select(ref mut select, _) => match select.body.select.as_mut() {
             OneSelect::Values(ref mut values) => values,
@@ -141,8 +150,6 @@ pub fn translate_insert(
     let halt_label = program.allocate_label();
     let loop_start_label = program.allocate_label();
 
-    let inserting_multiple_rows = values.len() > 1;
-
     // Multiple rows - use coroutine for value population
     if inserting_multiple_rows {
         let yield_reg = program.alloc_register();

core/translate/mod.rs

@@ -232,7 +232,9 @@ pub fn translate_inner(
         ast::Stmt::Release(_) => bail_parse_error!("RELEASE not supported yet"),
         ast::Stmt::Rollback { .. } => bail_parse_error!("ROLLBACK not supported yet"),
         ast::Stmt::Savepoint(_) => bail_parse_error!("SAVEPOINT not supported yet"),
-        ast::Stmt::Select(select) => translate_select(query_mode, schema, *select, syms, program)?,
+        ast::Stmt::Select(select) => {
+            translate_select(query_mode, schema, *select, syms, program)?.program
+        }
         ast::Stmt::Update(mut update) => translate_update(
             query_mode,
             schema,

core/translate/select.rs

@@ -19,13 +19,18 @@ use crate::{schema::Schema, vdbe::builder::ProgramBuilder, Result};
 use limbo_sqlite3_parser::ast::{self, CompoundSelect, SortOrder};
 use limbo_sqlite3_parser::ast::{ResultColumn, SelectInner};
 
+pub struct TranslateSelectResult {
+    pub program: ProgramBuilder,
+    pub num_result_cols: usize,
+}
+
 pub fn translate_select(
     query_mode: QueryMode,
     schema: &Schema,
     select: ast::Select,
     syms: &SymbolTable,
     mut program: ProgramBuilder,
-) -> Result<ProgramBuilder> {
+) -> Result<TranslateSelectResult> {
     let mut select_plan = prepare_select_plan(
         schema,
         select,
@@ -63,8 +68,12 @@ pub fn translate_select(
     };
 
     program.extend(&opts);
+    let num_result_cols = select.result_columns.len();
     emit_program(&mut program, select_plan, syms)?;
-    Ok(program)
+    Ok(TranslateSelectResult {
+        program,
+        num_result_cols,
+    })
 }
 
 pub fn prepare_select_plan<'a>(