Membuat Login & Logout dengan script PHP

1.  Inilah Script PHP untuk Login:

<?php

      session_start();

      include "config/konek.php";

      include "config/functions.php";

     

      if (isset($_POST['login'])) {

            $user       = $_POST['nama'];

            $password = md5($_POST['password']);

           

            $pesan="";

            $pesan.=cek_kosong($user,"nama masih kosong \\n");

            $pesan.=cek_kosong($password,"Password masih kosong \\n");

           

            if ($pesan <> "") {

                  back ($pesan);

                        exit;

           

            } else {

           

                  $sql  = "SELECT * FROM user WHERE nama='".$user."' AND password='".$password."'";

                 

                  $qry  = mysql_query($sql,$koneksi);

                  $num  = mysql_num_rows($qry);

                  $data = mysql_fetch_array($qry);

                 

                  if ($num == 1) {

                        $userid     = $data['id'];

                        $userlv     = $data['status'];

                       

                        session_register("userid");

                        session_register("userlv");

                       

                        header('location:home.php');

                  } else {

                        $pesan="nama dan Password anda tidak sesuai";

                        back ($pesan);

                  }

            }

      }

?>

b.  Inilah script PHP untuk Logout :

<?php

      session_start();

      session_destroy();

      header('location: index.php');

?>