SQL Server 觸發器初體驗

昨天面試時,機試有一題要求寫一個觸發器,之前沒寫過,那時只能寫出個基本語法,但功能實現有錯.今天把它實現了..

題目:T1表

CREATE TABLE [dbo].[t1] (
 [pid] [int] IDENTITY (1, 1) NOT NULL ,
 [price] [float] NOT NULL
) ON [PRIMARY]
GO

T2 表

CREATE TABLE [dbo].[t2] (
 [pid] [int] NOT NULL ,
 [pitemid] [int] IDENTITY (1, 1) NOT NULL ,
 [qty] [float] NOT NULL ,
 [psum] [float] NULL
) ON [PRIMARY]

要求寫一觸發器,插入或更新T2表QTY字段的值時,同時使得psum=qty*T1.Price

今天寫的觸發器代碼:

Create Trigger tg_sum
On dbo.t2
For Insert,Update
As
Update t2 Set psum=qty*price From t2 Inner Join t1 On t2.pid=t1.pid

初學觸發器,質量很差.