Question

在数据库中，参照完整性违约处理中有拒绝处理、级联修改、设为空值三种方法，那设置空值是如何定义的？

Answer 1

在数据库中，参照完整性违约处理中有拒绝处理、级联修改、设为空值三种方法，那设置空值是如何定义的:

这个是要自己定义的，自己写很麻烦,

下面是我用SQL SERVER逆向生成的代码,你可以看一下.

USE [stu]
GO
/****** 对象:  Table [dbo].[student]    脚本日期: 03/10/2011 14:52:53 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[student](
[id] [int] NOT NULL,
[did] [int] NULL,
CONSTRAINT [PK_student] PRIMARY KEY CLUSTERED
(
[id] ASC
)WITH (PAD_INDEX  = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]

GO
ALTER TABLE [dbo].[student]  WITH CHECK ADD  CONSTRAINT [FK_student_dd] FOREIGN KEY([did])
REFERENCES [dbo].[dd] ([Did])
ON UPDATE SET NULL
ON DELETE SET NULL
GO
ALTER TABLE [dbo].[student] CHECK CONSTRAINT [FK_student_dd]