From f138448da2ba39876c01b0d5d1a92cedfc054fb2 Mon Sep 17 00:00:00 2001
From: Pavan-Nambi <pavannambi999@gmail.com>
Date: Thu, 9 Oct 2025 08:09:31 +0530
Subject: [PATCH] don't allow duplicate col names in create table

---
 core/translate/schema.rs  | 13 +++++++++++++
 testing/create_table.test |  5 +++++
 2 files changed, 18 insertions(+)

diff --git a/core/translate/schema.rs b/core/translate/schema.rs
index a78e1b630..f7fde9f51 100644
--- a/core/translate/schema.rs
+++ b/core/translate/schema.rs
@@ -40,6 +40,19 @@ pub fn translate_create_table(
         bail_parse_error!("TEMPORARY table not supported yet");
     }
 
+    // maybe we can do better than this.
+    if let ast::CreateTableBody::ColumnsAndConstraints { columns, .. } = &body {
+        for i in 0..columns.len() {
+            let name1 = normalize_ident(columns[i].col_name.as_str());
+            for j in (i + 1)..columns.len() {
+                let name2 = normalize_ident(columns[j].col_name.as_str());
+                if name1 == name2 {
+                    bail_parse_error!("duplicate column name: {}", columns[i].col_name.as_str());
+                }
+            }
+        }
+    }
+
     // Check for STRICT mode without experimental flag
     if let ast::CreateTableBody::ColumnsAndConstraints { options, .. } = &body {
         if options.contains(ast::TableOptions::STRICT) && !connection.experimental_strict_enabled()
diff --git a/testing/create_table.test b/testing/create_table.test
index 7eb7bea7d..e961c017f 100755
--- a/testing/create_table.test
+++ b/testing/create_table.test
@@ -53,3 +53,8 @@ do_execsql_test_on_specific_db {:memory:} col-named-rowid {
   update t set rowid = 1; -- should allow regular update and not throw unique constraint
   select count(*) from t where rowid = 1;
 } {3}
+
+# https://github.com/tursodatabase/turso/issues/3637
+do_execsql_test_in_memory_any_error create_table_duplicate_column_names {
+    CREATE TABLE t(a, a);
+}
\ No newline at end of file