isTransactionExist example

    public function sSaveOrder()
    {
        $this->sComment = stripslashes($this->sComment ?? '');
        $this->sComment = stripcslashes($this->sComment);

        $this->sShippingData[CartKey::AMOUNT_NUMERIC] = $this->sShippingData[CartKey::AMOUNT_NUMERIC] ?? '0';

        if ($this->isTransactionExist($this->bookingId)) {
            return false;
        }

        // Insert basic-data of the order         $orderNumber = $this->sGetOrderNumber();
        $this->sOrderNumber = $orderNumber;

        if (!$this->sShippingcostsNumeric) {
            $this->sShippingcostsNumeric = 0.;
        }