try this...
$sqlhostname = "server"
$login = "user";
$password = "pass";
$base = "dbname";
$db_connect = mysql_connect($sqlhostname,$login,$password);
$base_selection = mysql_select_db($base,$db_connect);
$query = "UPDATE table_name SET contact_name ='$contact_name' WHERE job_id = '$job_id'";
$req = mysql_query($query);