public function fetchAll($key_column = null)
	{
		$result = $this->query();
		if ($key_column === null) {
			$list = $result->fetchAll(\PDO::FETCH_ASSOC);
		} else {
			$list = array();
			while(($item = $result->fetch(\PDO::FETCH_ASSOC))) {
				$list[$item[$key_column]] = $item;
			}
			return $list;
		}
		$result->closeCursor();
		return $list;
	}