feat: add delete, context, and tx helpers

Add Delete/DeleteAffected, context-aware CRUD helpers, WithTx, ContainsCol,
and queryReturning deduplication for returning statements.

Co-authored-by: Cursor <cursoragent@cursor.com>

exec.go

@@ -1,11 +1,19 @@
 package dbx
 
-import "errors"
+import (
+	"context"
+	"errors"
+)
 
 // Insert executes an insert statement, returning the last inserted ID or an
 // error if the insert fails.
 func Insert(sqlo Executable, stmt Statement) (uint64, error) {
-	res, err := stmt.Exec(sqlo)
+	return InsertContext(context.Background(), sqlo, stmt)
+}
+
+// InsertContext is the context-aware variant of [Insert].
+func InsertContext(ctx context.Context, sqlo Executable, stmt Statement) (uint64, error) {
+	res, err := stmt.ExecContext(ctx, sqlo)
 	if err != nil {
 		return 0, err
 	}
@@ -26,24 +34,34 @@ func Insert(sqlo Executable, stmt Statement) (uint64, error) {
 // The statement MUST be a Jet InsertStatement with a RETURNING clause. Returns
 // the inserted row object T or an error if the insert fails or no rows are returned.
 func InsertReturning[T any](sqlo Queryable, stmt Statement) (*T, error) {
-	var result T
-	err := stmt.Query(sqlo, &result)
-	if err != nil {
-		return nil, err
-	}
-	return &result, nil
+	return InsertReturningContext[T](context.Background(), sqlo, stmt)
+}
+
+// InsertReturningContext is the context-aware variant of [InsertReturning].
+func InsertReturningContext[T any](ctx context.Context, sqlo Queryable, stmt Statement) (*T, error) {
+	return queryReturningContext[T](ctx, sqlo, stmt)
 }
 
 // Update executes an update statement, returning an error if the update fails.
 func Update(sqlo Executable, stmt Statement) error {
-	_, err := stmt.Exec(sqlo)
+	return UpdateContext(context.Background(), sqlo, stmt)
+}
+
+// UpdateContext is the context-aware variant of [Update].
+func UpdateContext(ctx context.Context, sqlo Executable, stmt Statement) error {
+	_, err := stmt.ExecContext(ctx, sqlo)
 	return err
 }
 
 // UpdateAffected executes an update statement and returns the number of rows
 // affected and an error if any.
 func UpdateAffected(sqlo Executable, stmt Statement) (int64, error) {
-	res, err := stmt.Exec(sqlo)
+	return UpdateAffectedContext(context.Background(), sqlo, stmt)
+}
+
+// UpdateAffectedContext is the context-aware variant of [UpdateAffected].
+func UpdateAffectedContext(ctx context.Context, sqlo Executable, stmt Statement) (int64, error) {
+	res, err := stmt.ExecContext(ctx, sqlo)
 	if err != nil {
 		return 0, err
 	}
@@ -60,9 +78,49 @@ func UpdateAffected(sqlo Executable, stmt Statement) (int64, error) {
 // The statement MUST be a Jet UpdateStatement with a RETURNING clause. Returns
 // the updated row object T or an error if the update fails or no rows are returned.
 func UpdateReturning[T any](sqlo Queryable, stmt Statement) (*T, error) {
-	var result T
-	err := stmt.Query(sqlo, &result)
+	return UpdateReturningContext[T](context.Background(), sqlo, stmt)
+}
+
+// UpdateReturningContext is the context-aware variant of [UpdateReturning].
+func UpdateReturningContext[T any](ctx context.Context, sqlo Queryable, stmt Statement) (*T, error) {
+	return queryReturningContext[T](ctx, sqlo, stmt)
+}
+
+// Delete executes a delete statement, returning an error if the delete fails.
+func Delete(sqlo Executable, stmt Statement) error {
+	return DeleteContext(context.Background(), sqlo, stmt)
+}
+
+// DeleteContext is the context-aware variant of [Delete].
+func DeleteContext(ctx context.Context, sqlo Executable, stmt Statement) error {
+	_, err := stmt.ExecContext(ctx, sqlo)
+	return err
+}
+
+// DeleteAffected executes a delete statement and returns the number of rows
+// affected and an error if any.
+func DeleteAffected(sqlo Executable, stmt Statement) (int64, error) {
+	return DeleteAffectedContext(context.Background(), sqlo, stmt)
+}
+
+// DeleteAffectedContext is the context-aware variant of [DeleteAffected].
+func DeleteAffectedContext(ctx context.Context, sqlo Executable, stmt Statement) (int64, error) {
+	res, err := stmt.ExecContext(ctx, sqlo)
 	if err != nil {
+		return 0, err
+	}
+
+	rowsAffected, err := res.RowsAffected()
+	if err != nil {
+		return 0, err
+	}
+
+	return rowsAffected, nil
+}
+
+func queryReturningContext[T any](ctx context.Context, sqlo Queryable, stmt Statement) (*T, error) {
+	var result T
+	if err := stmt.QueryContext(ctx, sqlo, &result); err != nil {
 		return nil, err
 	}
 	return &result, nil