From 1569116e3e926315895200adce60eccf858690a8 Mon Sep 17 00:00:00 2001
From: Charlie Tonneslan <cst0520@gmail.com>
Date: Sat, 16 May 2026 08:18:23 -0400
Subject: [PATCH] Fix wrong arg count in Exec's "not enough args" error

The Exec and Query paths share the same multi-statement loop and the
same `len(args)-start < na` check, but the Exec error message was
printing `len(args)` instead of `len(args)-start`. With one arg passed
to a two-statement query like `SELECT ?; SELECT ?`, the first statement
consumes the arg and the second one trips the check, so the "got" count
should be 0 (args remaining), not 1 (total args originally passed).

The Query path was already correct. This just brings Exec in line.

Closes #1395

Signed-off-by: Charlie Tonneslan <cst0520@gmail.com>
---
 sqlite3.go      |  2 +-
 sqlite3_test.go | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/sqlite3.go b/sqlite3.go
index b9deb72a..d44ae15f 100644
--- a/sqlite3.go
+++ b/sqlite3.go
@@ -962,7 +962,7 @@ func (c *SQLiteConn) exec(ctx context.Context, query string, args []driver.Named
 			na := s.NumInput()
 			if len(args)-start < na {
 				s.Close()
-				return nil, fmt.Errorf("not enough args to execute query: want %d got %d", na, len(args))
+				return nil, fmt.Errorf("not enough args to execute query: want %d got %d", na, len(args)-start)
 			}
 			stmtArgs := stmtArgs(args, start, na)
 			res, err = s.(*SQLiteStmt).exec(ctx, stmtArgs)
diff --git a/sqlite3_test.go b/sqlite3_test.go
index ac81458c..c1874225 100644
--- a/sqlite3_test.go
+++ b/sqlite3_test.go
@@ -1090,6 +1090,38 @@ func TestExecer(t *testing.T) {
 	}
 }
 
+func TestExecNotEnoughArgsErrorMessage(t *testing.T) {
+	tempFilename := TempFilename(t)
+	defer os.Remove(tempFilename)
+	db, err := sql.Open("sqlite3", tempFilename)
+	if err != nil {
+		t.Fatal("Failed to open database:", err)
+	}
+	defer db.Close()
+
+	// Second statement is missing its arg. The "got" count should reflect
+	// the args remaining after the first statement consumed one, not the
+	// total number of args originally passed in.
+	_, err = db.Exec("SELECT ?; SELECT ?", "hello")
+	if err == nil {
+		t.Fatal("expected error for missing arg")
+	}
+	want := "not enough args to execute query: want 1 got 0"
+	if err.Error() != want {
+		t.Errorf("Exec error message:\n got: %q\nwant: %q", err.Error(), want)
+	}
+
+	// Query already reports the right number; check it stays that way so
+	// the two paths don't drift again.
+	_, err = db.Query("SELECT ?; SELECT ?", "hello")
+	if err == nil {
+		t.Fatal("expected error for missing arg")
+	}
+	if err.Error() != want {
+		t.Errorf("Query error message:\n got: %q\nwant: %q", err.Error(), want)
+	}
+}
+
 func TestQueryer(t *testing.T) {
 	tempFilename := TempFilename(t)
 	defer os.Remove(tempFilename)