public function orderBy($key, $direction = 'ASC')
    {
        if (Helpers\Validate::table($this->name)->field($key))
        {
            $directions                        = array(
                'ASC'  => SORT_ASC,
                'DESC' => SORT_DESC
            );
            $this->pending[__FUNCTION__][$key] = isset($directions[$direction]) ? $directions[$direction] : 'ASC';
        }

        return $this;
    }