public function getCategories()
    {
        if (is_null($this->_aCatIds)) {
            $oDb = \OxidEsales\Eshop\Core\DatabaseProvider::getDb();
            $sQ = "select oxobjectid from oxobject2delivery where oxdeliveryid=" . $oDb->quote($this->getId()) . " and oxtype = 'oxcategories'";
            $aCatIds = $oDb->getCol($sQ);
            $this->_aCatIds = $aCatIds;
        }

        return $this->_aCatIds;
    }