如何在 pl sql 中进行更新触发查询

Question

I have 2 tables (1) product_warehouse and (2) Return_Vendor Invoice . i have to update the quantity in product_warehouse by trigger according to the value of Return_Vendor Invoice Table. where Item_code is unique key in both tables.

For example if the product_warehouse contain 3 quantities , and the shopkeeper returns 1 quantity to vendor then it should be 2 in the Product_warehouse . update query will also acceptable.

Answer 1

create or replace trigger tiuda_return_vendor after insert or update or delete
on return_vendor is
begin
  update product_wherehouse
  set
    quantity = quantity - (:new.quantity - nvl(:old.quantity, 0)
  where
    item_code = nvl(:new.item_code, :old.item_code);
end;

This trigger works in most cases. You can insert update or delete the return line.

Only thing is: when updating, you cannot update the item_code itself, because the update statement doesn't take that into account. You could easily solve that, but I don't know if it's in your requirements. I usually don't change values like that, but rather remove the item and add a new line for a different item.

Updating the quantity works fine. If you update the quantity, the difference between old and new is calculated and that difference is used to modify the stock quantity in the wherehouse.

Answer 2

create or replace
TRIGGER "WR_RETURN_INVOICE_UPDATE_TRG" 
AFTER UPDATE ON RETURN_INVOICE
FOR EACH ROW
  BEGIN
    UPDATE PRODUCT_WAREHOUSE
    SET QUANTITY=QUANTITY-:OLD.QUANTITY
    WHERE ITEM_CODE=:OLD.ITEM_CODE;   
END WR_RETURN_INVOICE_UPDATE_TRG;



Try this one it will works.