public function offsetGet($offset)
    {
        if (!is_int($offset)) {
            throw new \Erebot\InvalidValueException('An integer was expected');
        }

        $this->getQuery->execute(array(':offset' => $offset));
        $res = $this->getQuery->fetchColumn();
        $this->getQuery->closeCursor();

        if ($res == '' || $res === null || $res === false) {
            return null;
        }
        return $res;
    }