使用触发器来获取GETDATE()

Question

我正在使用Trigger将Products表更新为当前日期,如果该列的值为null.我还有一切,当我将新值插入表中时,DateAdded列为NULL而不是今天的当前日期.我不确定什么是错的,为什么它不起作用.任何帮助将不胜感激,谢谢!

IF OBJECT_ID('Products_INSERT') IS NOT NULL
DROP TRIGGER Products_INSERT

CREATE TRIGGER Products_INSERT
ON Products 
AFTER INSERT
AS
UPDATE Products
SET DateAdded = GETDATE()
WHERE DateAdded = NULL;

Answer 1

我希望触发器看起来像这样:

CREATE TRIGGER INSERT_Products ON Products 
AFTER INSERT
AS BEGIN
    UPDATE Products
        SET DateAdded = GETDATE()
        FROM Products p JOIN
             Inserted i
             ON p.productid = i.productid;
END;

如果要测试未在以下位置设置该值insert:

CREATE TRIGGER INSERT_Products ON Products 
AFTER INSERT
AS BEGIN
    UPDATE Products
        SET DateAdded = GETDATE()
        FROM Products p JOIN
             Inserted i
             ON p.productid = i.productid
        WHERE DateAdded IS NOT NULL;
END;

也就是说,我只会使用默认值 -

create table Products (
    ProductId int identity primary key,
    . . . 
    DateAdded datetime not null default getdate()
);

比触发器简单得多,这仍然允许您使用自己的值覆盖默认值.