CLASS AUTHENTIFICATION PHP5 POO

//*** CREE PAR MOUNIR R'QUIBA (MOON AIR) (cosmoswarez@msn.com) ********
//          31/08/2009 !! COPYRIGHT !!
//--------A utiliser sans moderation :D -------------------------------
// Class d'authentification   
// 

<?php

/*
* fichier Auth.php
*/
class Auth{

   static function isLogged(){
      if(isset($_SESSION['Auth']) and isset($_SESSION['Auth']['login']) and isset($_SESSION['Auth']['pass'])){
        extract($_SESSION['Auth']);
        $sql = "SELECT * FROM users WHERE login='$login' AND pass='$pass' LIMIT 1";
        $req = mysql_query($sql) or die(mysql_error());
        if(mysql_num_rows($req) > 0){
            return true;
        }
        return false;
      }
      return false;
   }
   
   static function levelZone(){
      if(isset($_SESSION['Auth']) and isset($_SESSION['Auth']['login']) and isset($_SESSION['Auth']['pass'])){
        extract($_SESSION['Auth']);
        $sql = "SELECT login,pass,level FROM users WHERE login='$login' AND pass='$pass' LIMIT 1";
        $req = mysql_query($sql) or die(mysql_error());
        if(mysql_num_rows($req) > 0){
           $data = mysql_fetch_assoc($req); 
           if($data['level']>=1 && $data['level']<=3) return $data['level'];              
        }
        return false;
      }
      return false;
      
   }

}
?>

<?php
/*
* index.php
*/
session_start();
mysql_connect('localhost','root','');
mysql_select_db('cat');
mysql_query('SET NAMES 'utf8'');
include './Auth.php';
 
$login ='moonair';
$pass = 'moonair';
  
$_SESSION['Auth'] = array(
  "login"=>$login,
  "pass"=>$pass
);

if(Auth::isLogged()){
  echo 'Vous etes identifier<br />';
  echo 'Level : '.Auth::levelZone().'<br />';
  switch(Auth::levelZone()){               
             case "1":
                echo 'Administrateur<br />';
                break;
             case "2":
                echo 'Membre<br />';
                break;
             case "3":
                echo 'Membre Premium<br />';
                break;
  }
}else{
  echo 'Non identifier<br />';
}
?>