php中的登陆login实例代码

<?php 
require "../include/dbclass.php"; 
$username=$_post['username']; 
$password=$_post['password']; 
if(empty($username) || empty($password)){ 
 go_msg("请填写用户名，密码！","../default.html"); 
 exit; 
 } 
dbconn(); 
$password=md5($password); 
$sql = "select username,usertype,userpass from siteuser where username='" . $username ."' and userpass='" . $password . "' and isopen=1"; 
//echo "$sql"; 
$result = $db -> exec_sql($sql); 
 $total=mysql_num_rows($result); 
 if($total==0){ 
 dbclose(); 
 go_msg("注册用户还没有通过管理员审核或用户名及密码不符！请重新输入！","../default.html"); 
 exit; 
 }else{ 
 $rs = $db -> fetch_array($result); 
 //附值，并登录 
 session_register("username"); 
 session_register("usertype"); 
 $_session["usertype"]=$rs['usertype']; 
 $_session["username"]=$username; 
 //echo $_session["username"]; 
 if ($_session["usertype"]==1){ 
  go_msg("登陆成功！","default.php"); 

  //header('location:http://163.com'); 
 } 
 if ($_session["usertype"]==2){ 
   go_msg("登陆成功！","../user2/default_1.php"); 
 } 
 if ($_session["usertype"]==3){ 

   go_msg("登陆成功！","../user3/default_2.php"); 
 } 
 // header('location:default.php'); 
 } 
dbclose(); 
// 何问起 hovertree.com
?>