ดูให้หน่อยครับ ทีแรกใช้ session ก็ได้นะครับ แต่พอเปลี่ยนมาใช้ coockie แล้ว ไม่ได้พอล็อกอินถูก ก้ไม่

/**
 * จัดการเรื่อง session และ cookie สำหรับผู้ใช้ระบบ
 */
if ($_COOKIE['user'] AND ! $_SESSION['user'])
{
	try
	{
		$temp = get_magic_quotes_gpc() ? unserialize(stripslashes($_COOKIE['user'])) : unserialize($_COOKIE['user']);
		
		// สร้าง sql
		if ($temp['type'] === 'member')
		{
			$sql = "SELECT member_id, member_uname, member_upass FROM member WHERE member_uname='".$temp['uname']."' AND member_upass='".$temp['upass']."' AND member_status='Y'";
		}
		elseif ($temp['type'] === 'admin')
		{
			$sql = "SELECT admin_id, admin_uname, admin_upass FROM admin WHERE admin_uname='".$temp['uname']."' AND admin_upass='".$temp['upass']."' AND admin_status='Y'";
		}
		elseif ($temp['type'] === 'hotel')
		{
			$sql = "SELECT hotel_id, hotel_uname, hotel_upass FROM hotel WHERE hotel_uname='".$temp['uname']."' AND hotel_upass='".$temp['upass']."' AND hotel_status='Y'";
		}
		else
		{
			throw new Exception('cookie ผิดพลาด');
		}
		
		// ตรวจสอบผู้ใช้
		$query = mysql_query($sql);
		if ($row = mysql_fetch_array($query))
		{
			$row = Util::stripslashes_all($row);
			
			$arr = array(
				'id'          => $row[0],
				'uname'   => $row[1],
				'upass'     => $row[2],
				'type'      => $temp['type']
			);
			
			// ตั้งค่า session user 
			$_SESSION['user'] = $arr;
			
			// ต่อเวลา cookie
			setcookie('user', serialize($_SESSION['user']), (time() + $config['cookie_expire']));
		}
	}
	catch (Exception $ex)
	{}
}
elseif ($_COOKIE['user'] AND $_SESSION['user'])
{
	// ต่อเวลา cookie
	setcookie('user', serialize($_SESSION['user']), (time() + $config['cookie_expire']));
}

public function action_logging()
	{
		if ( ! empty($_POST['uname']) AND ! empty($_POST['upass']))
		{
			$model = new Model_Admin;
			$is_admin = $model->check_admin($_POST['uname'], md5($_POST['upass']));
			
			if ($is_admin)
			{
				Session::instance()
					->set('admin_uname', $_POST['uname'])
					->set('admin_upass', md5($_POST['upass']));
				
				if ( ! empty($_POST['remember']))
				{
					Cookie::set('admin_uname', $_POST['uname'], User::COOKIE_EXPIRE);
					Cookie::set('admin_upass', md5($_POST['upass']), User::COOKIE_EXPIRE);
				}
				
				$this->request->redirect(URL::site('manage'));
				return;
			}
		}
		
		$this->action_index('Username หรือ Passord ไม่ถูกต้อง');
	}

class Model_Admin extends Kohana_Model
{
	public function check_admin($uname, $upass)
	{
		$sql = sprintf(
			"SELECT * FROM admin ".
			"WHERE admin_uname = %s ".
			"AND admin_upass = %s",
			$this->_db->escape($uname),
			$this->_db->escape(md5($upass))
		);
		
		$rs = $this->_db->query(Database::SELECT, $sql, FALSE);
		
		return $rs->count() ? TRUE : FALSE;
	}
	
}

class User
{
	// 15 days seconds
	const COOKIE_EXPIRE = 1296000;
		
	public static function is_admin()
	{
		if ( ! is_null(Session::instance()->get('admin_uname')) AND ! is_null(Session::instance()->get('admin_upass')))
		{
			return TRUE;
		}
		elseif ( ! is_null(Cookie::get('admin_uname')) AND ! is_null(Cookie::get('admin_upass')))
		{
			$model = new Model_Admin;
				
			$is_admin = $model->check_admin(Cookie::get('admin_uname'), Cookie::get('admin_upass'));
			if ($is_admin)
			{
				Session::instance()->set('admin_uname', Cookie::get('admin_uanme'));
				Session::instance()->set('admin_upass', Cookie::get('admin_upass'));
				
				return TRUE;
			}
		}
		
		return FALSE;	
	}
	
	public static function add_admin_cookie_time()
	{
		if ( ! is_null(Cookie::get('admin_uname')) AND ! is_null(Cookie::get('admin_upass')))
		{
			Cookie::set('admin_uname', Cookie::get('admin_uname'), User::COOKIE_EXPIRE);
			Cookie::set('admin_upass', Cookie::get('admin_upass'), User::COOKIE_EXPIRE);
		}
	}
	
	public static function clear_admin_cookie_session()
	{
		// delete cookie
		Cookie::delete('admin_uname');
		Cookie::delete('admin_upass');
		
		// delete session
		Session::instance()
			->delete('admin_uname')
			->delete('admin_upass');
	}
}