public function logAccess()
    {
        $this->db->executeUpdate(
                "update nb_site_user "
                 . "set nb_site_user_last_login_datetime=now() "
               . "where nb_site_id=%site_id\$d "
                 . "and nb_role_id=%role_id\$d "
                 . "and nb_user_id=%user_id\$d",
                array(
                    'site_id' => $this->getValue('nb_site_id'),
                    'role_id' => $this->getValue('nb_role_id'),
                    'user_id' => $this->getValue('nb_user_id')
                )
        );
    }