php+mysql 实现身份验证代码

<?php
$uname=$_POST["username"];
$pwd=$_POST["password"];
$link = mysql_connect(localhost, root, 123456)
or die(Could not connect: . mysql_error());
mysql_select_db(ruida) or die(Could not select database);
// 执行 SQL 查询
$query = SELECT * FROM user;
$result = mysql_query($query) or die(Query failed: . mysql_error());
while($row=mysql_fetch_array($result)){
if($uname==$row[username] && $pwd==$row[password])
{
//页面跳转
}
else
echo error!;}
// 释放结果集
mysql_free_result($result);
// 关闭连接
mysql_close($link);
?>