Codeigniter用户访问级别

Question

型号：

Class User extends CI_Controller
{
    function login($username, $password)
    {
        $this->db->select('id', 'username', 'password', 'access');
        $this->db->from('users');
        $this->db->where('username', $username);
        $this->db->where('password', MD5($password));
        $this->db->limit(1);

        $query = $this->db->get();

        if($query->num_rows() == 1)
        {
            return $query->result();
        }
        else
        {
            return false;
        }
    }
}

控制器：

class VerifyLogin extends CI_Controller {
    function __construct()
    {
        parent::__construct();
        $this->load->library('form_validation');
        $this->load->model('user','',TRUE);
    }

    function index()
    {
        $this->form_validation->set_rules('username', 'Username', 'trim|required|xss_clean');
        $this->form_validation->set_rules('password', 'Password', 'trim|required|xss_clean|callback_check_database');

        if($this->form_validation->run() == FALSE)
        {
            //Field validation failed.  User redirected to login page
            $this->load->view('login_view');
        }

        else
        {
            //Go to private area
            redirect('home', 'refresh');
        }

    }

    function check_database($password)
    {
        //Field validation succeeded.  Validate against database
        $username = $this->input->post('username');

        //query the database
        $result = $this->user->login($username, $password);

        if($result)
        {
            $sess_array = array();
            foreach($result as $row)
            {
                $sess_array = array(
                    'id' => $row->id,
                    'username' => @$row->username
                );
                $this->session->set_userdata('logged_in', $sess_array);
            }
            return TRUE;
        }
        else
        {
            $this->form_validation->set_message('check_database', 'Invalid username or password');
            return false;
        }
    }
}

如何处理访问？在数据库中是int数字，你需要从基数中进行选择，从表中获取数字并访问与他一起工作。如何实现呢？