Fatal error: Call to undefined method CI_DB_mysqli_result::fetch()

Fatal error: Call to undefined method CI_DB_mysqli_result::fetch()

    public function getVoters($limit = 5)
    {
        $db = $this->load->database("cms", true);

                $year = date('Y');
                $month = date('n');

                $res = $this->db->query("SELECT account, counter FROM votecounter WHERE year=$year AND month=$month ORDER BY counter DESC LIMIT 5");

                $x = 1;

                while ($arr = $res->fetch())
                {
                    $accid = $arr['account'];

                    $res2 = $DB->prepare("SELECT `displayName` FROM `account_data` WHERE `id` = :acc LIMIT 1;");
                    $res2->bindParam(':acc', $accid, PDO::PARAM_STR);
                    $res2->execute();

                    $arr2 = $res2->fetch();

                    echo '
                        <li>
                            <p>', $x ,'</p>
                            <a href="', $config['BaseURL'], '/index.php?page=profile&uid=', $accid, '">', $arr2['displayName'] ,'</a>
                            <span>', $arr['counter'] ,' <i>Votes</i></span>
                        </li>';
                    $x++;
                    unset($res2, $arr2, $accid);
                }
                unset($res, $x);    
}

这曾经在我拥有的 PHP 网站上工作,但是我更改为使用 Smarty/Codeigniter 构建的新网站并且此错误一直出现,我不知道如何修复它.

Fatal error: Call to undefined method CI_DB_mysqli_result::fetch()

任何帮助将不胜感激..

如果我没有记错的话,codeigniter 中没有 fetch() 函数。

所以也许可以使用 result_array()