/**
  * Add tax if it exists in AbstractProduct. If no tax - delete it.
  * @param AbstractProduct $abstractProduct
  * @param String $reference
  */
 private function setTax($abstractProduct, $reference)
 {
     global $adb;
     $inventoryId = $this->trimReference($reference);
     if ($abstractProduct->isNDS()) {
         $params = array($inventoryId, self::NDS_TAX_ID, $abstractProduct->getNDS());
         $query = "insert into vtiger_producttaxrel values(?,?,?)";
         $adb->pquery($query, $params);
     } else {
         $params = array($inventoryId);
         $query = "delete from vtiger_producttaxrel where productid='?'";
         $adb->pquery($query, $params);
     }
 }