public function markOrderPaid()
    {
        parent::_setOrderStatus(self::OEPAYPAL_TRANSACTION_STATUS_OK);

        $db = \OxidEsales\Eshop\Core\DatabaseProvider::getDb();
        $utilsDate = \OxidEsales\Eshop\Core\Registry::getUtilsDate();
        $date = date('Y-m-d H:i:s', $utilsDate->getTime());

        $query = 'update oxorder set oxpaid=? where oxid=?';
        $db->execute($query, array($date, $this->getId()));

        //updating order object
        $this->oxorder__oxpaid = new \OxidEsales\Eshop\Core\Field($date);
    }