Ver original$code = $_POST['codigo'];$query = mysql_query('select * from tblcodes where Code = "'.$code.'" and usado = "0"',$conexion) or die(mysql_error());if (mysql_num_rows($query) == 1) {mysql_query('update tblcodes set usado = 1 where Code = "'.$code.'"',$conexion) or die (mysql_error());echo 'código valido y sin usar';}else {echo 'código invalido o ya usado';}