protected function getPdoStatement()
    {
        $statement = $this->connection->prepare($this->getSql());
        if ($this->dataRowClass !== null) {
            $statement->setFetchMode(PDO::FETCH_CLASS, $this->dataRowClass);
        } else {
            $statement->setFetchMode(PDO::FETCH_OBJ);
        }
        return $statement;
    }