public function only()
    {
        //Only colname
        $cols = func_get_args();
        $dstore = new DataStore;

        foreach ($this->rows as $row) {
            $new_row = array();
            foreach ($cols as $col) {
                $new_row[$col] = $row[$col];
            }
            $dstore->push($new_row);
        }
        $columnsMeta = Utility::get($this->metaData, "columns");
        $newColumnsMeta = array();
        if ($columnsMeta) {
            foreach ($cols as $col) {
                $newColumnsMeta[$col] = $columnsMeta[$col];
            }
        }
        $dstore->meta(array("columns"=>$newColumnsMeta));
        return $dstore;
    }