PHP SQL更新语句

<?php
if ($wid!=""){  //确认工资条没有问题
$y_title="1";
$sql= "update wage set Signature='$y_title' wherewid='$wid'";
mysql_query($sql) or die(mysql_error());
echo("<script type='text/javascript'>alert('确认成功！');location.href='view_wage.php';</script>");
mysql_close();
}
?>