<?phpsession_start();$conn=mysql_connect("localhost","root","root");mysql_select_db("ww",$conn);mysql_query("set names gb2312");if(isset($_POST['submit']) && $_POST['submit']=="提交"){    if($_POST['admin_new_pass']!=""){   if($_POST['admin_new_pass2']!=""){ /*$sql="update admin set admin_pass='".$_POST['admin_new_pass']."' where admin_user='".$_POST['admin_user']."'";*/  $admin_pass=$_POST['admin_new_pass']; $admin_user=$_POST['admin_user'];

$sql="update admin set admin_pass='$admin_pass' where admin_user='{$_POST['admin_user']}'"; //打印sql语句,在phpmyadmin里面运行下,看报不报错 echo $sql;exit;
        $result=mysql_query($sql); if($result!==0){ echo"<script language='javascript'>alert('密码修改成功'); window.location.href='index.php';</script>"; } else{ echo"<script language='javascript'>alert('密码修改失败'); history.back();</script>";    } } }}?>
输出结果是    update admin set admin_pass='qq123456' where admin_user=''     请问该怎么改?????