note 19968 added to function.set-time-limit

I use php in database. It show fatal error:Maximum execution time of seconds exceeded at $num_rows = mysql_num_rows($dbname,$sql) and I read you help I call me you set_time_limit() I type set_time_limit(20) before this error but I show me this error again please help me (thank you very much!!) linky at thailand -- http://www.php.net/manual/en/function.set-time-limit.php http://master.php.net/manage/user-notes.php?action=edit+19968 http://master.php.net/manage/user-notes.php?action=delete+19968 http://master.php.net/manage/user-notes.php?action=reject+19968