/* edit the purchase items */
        WHILE items_index<items_length DO
            UPDATE PurchaseOrderItems SET quantity=JSON_EXTRACT(p_purchaseitems, CONCAT('$[',items_index,'].quantity')) ,products_productid=JSON_EXTRACT(p_purchaseitems, CONCAT('$[',items_index,'].productid')) WHERE itemid=JSON_EXTRACT(p_purchaseitems, CONCAT('$[',items_index,'].purchaseitemid'));
            IF items_index+1=items_length THEN
                /* condition will only be true in last iteration*/
                SET item_separator='';
            END IF;
            SET save_list = CONCAT(save_list,JSON_EXTRACT(p_purchaseitems, CONCAT('$[',items_index,'].purchaseitemid')),item_separator);
            SET items_index=items_index+1;
        END WHILE;
        /* delete all other items that were not in the list */
        DELETE FROM PurchaseOrderItems WHERE purchaseorders_purchaseorderid=p_purchaseorderid AND itemid not in (save_list);