php 检验登陆类

<?php

class checklogin
{
   var $name;
   var $pwd;

   function __construct($username,$password)
   {
     $this->name=$username;
     $this->pwd=$password;
   }

   function checkinput()
   {
     global $db;
     $sql="select * from tb_manager where name='$this->name' and pwd='$this->pwd'";
     $res=$db->query($sql);
     $info=$db->fetch_array($res); 
     if($info['name']==$this->name and $info['pwd']==$this->pwd)
     {
         $_SESSION[admin_name]=$info[name];
         $_SESSION[pwd]=$info[pwd];
         echo "<script>alert('登录成功！);window.location.href='index.php';</script>";
     }
     else
     {
         echo "<script language='javascript'>alert('登录失败！');history.back();</script>";
         exit;
     }
   }

}

?>
//该片段来自于http://outofmemory.cn