SQL Server 2005觸發器不能正常工作

Question

我有一個名爲order_details的表和另一個表book_inventory。

如果有時我quantity_ordered在order_details它應該從從quantity_in_stock減少該值。

這裏是我的代碼：

create TRIGGER [dbo].[book] 
    ON [dbo].[order_details] 
    AFTER UPDATE 
AS 

IF UPDATE(quantity_ordered) 
    UPDATE book_inventory 
    SET book_inventory.quantity_in_stock = book_inventory.quantity_in_stock - order_details.quantity_ordered 
    FROM order_details 
    WHERE book_inventory.isbn = order_details.isbn 

Answer 1

好吧，seemes對我說，寫這個查詢的正確方法是將

create TRIGGER [dbo].[book] 
    ON [dbo].[order_details] 
    AFTER UPDATE 
AS 

IF UPDATE(quantity_ordered) 
    UPDATE book_inventory 
    SET book_inventory.quantity_in_stock = book_inventory.quantity_in_stock - i.quantity_ordered + d.quantity_ordered 
    FROM INSERTED i 
    JOIN DELETED d 
     ON d.isbn = i.isbn 
    WHERE book_inventory.isbn = i.isbn