protected function _isArticleAssigned($oArticle)
    {
        $oDb = \OxidEsales\Eshop\Core\DatabaseProvider::getDb();
        $sDiscountIdQuoted = $oDb->quote($this->oxdiscount__oxid->value);

        $sQ = "select 1
                from oxobject2discount
                where oxdiscountid = {$sDiscountIdQuoted} and oxtype = 'oxarticles' ";
        $sQ .= $this->_getProductCheckQuery($oArticle);

        return $oDb->getOne($sQ) ? true : false;
    }