Think\Db\Builder::parseOrder PHP Метод

    protected function parseOrder($order, $options = [])
    {
        if (is_array($order)) {
            $array = [];
            foreach ($order as $key => $val) {
                if (is_numeric($key)) {
                    if (false === strpos($val, '(')) {
                        $array[] = $this->parseKey($val, $options);
                    } elseif ('[rand]' == $val) {
                        $array[] = $this->parseRand();
                    }
                } else {
                    $sort = in_array(strtolower(trim($val)), ['asc', 'desc']) ? ' ' . $val : '';
                    $array[] = $this->parseKey($key, $options) . ' ' . $sort;
                }
            }
            $order = implode(',', $array);
        }
        return !empty($order) ? ' ORDER BY ' . $order : '';
    }