关于PHP问题

哪里错了？我输入正确的可他还是提示我输入的不正确
<?php include_once('conn.php');
$name = @$_GET['username'];
$password = @md5($_GET['password']);
$sql = "SELECT * FROM mytext";
$res = mysql_query($sql);
while($row = mysql_fetch_array($res))
{
if($row['username']===$name&&$row['password']===$password)
{
echo "<script> alert('倒霉的人一向都可以登陆成功的！!');this.location.href='admin_index.php'; </script>";
}
else
{
echo "<script> alert('恭喜您,帐号不存在或密码错误,请重新输入!!');this.location.href='login.php'; </script>";
}
}
?>