public function get($index=0,$colName=null)
    {
        if (isset($this->rows[$index])) {
            if ($colName!==null) {
                if (isset($this->rows[$index][$colName])) {
                    return $this->rows[$index][$colName];
                }
            } else {
                return $this->rows[$index];
            }
        }
        return null;
    }