public function sqlOrders()
    {
        if (!$this->hasOrders()) {
            return '';
        }

        $parts = [];
        foreach ($this->orders() as $order) {
            if (!$order instanceof DatabaseOrder) {
                $order = $this->createOrder($order->data());
            }

            $sql = $order->sql();
            if (strlen($sql) > 0) {
                $parts[] = $sql;
            }
        }

        if (empty($parts)) {
            return '';
        }

        return ' ORDER BY '.implode(', ', $parts);
    }