private function getCached() {
        if (isset($_GET['noCache'])) return null;
        $cacheDir = DATA . 'select' . DIRECTORY_SEPARATOR;
        if (!is_dir($cacheDir)) mkdir($cacheDir, 0777, true);

        $cache = $cacheDir . base64_encode($this->getName()) . '.php';
        if (!is_readable($cache)) return null;
        $cached = include $cache;
        return $this->decode($cached[$this->encode($this->query . serialize($this->values))]);
    }