php中的登陆login_php技巧

login
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();

?>