MySQL update using PDO and prepared statement not working

Question

I\'m having a strange problem with php PDO and mysql.

I have the following table:

create table test_table ( id integer, value text );

Answer 1

$maker_id=1;
$stmt = $db->prepare("UPDATE car_details SET maker_id=?");
$affected_rows=$stmt->execute(array($maker_id));
echo $affected_rows.' were affected';