常用SQL語句收藏

視圖的創建刪除與使用

創建:
create view view_1 as SELECT     dbo.class.class, dbo.class.studentnumber, dbo.class.teacher, dbo.student.id, dbo.student.name, dbo.student.age, dbo.student.english, 
                      dbo.student.born, dbo.student.class AS Expr1 
FROM         dbo.class INNER JOIN
                      dbo.student ON dbo.student.class = dbo.class.class
使用: select * from view_1
刪除:drop view view_1

觸發器創建

set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go
CREATE  TRIGGER [trigger_1] 
   ON  [dbo].[class]
   AFTER DELETE
AS 
BEGIN
	-- SET NOCOUNT ON added to prevent extra result sets from
	-- interfering with SELECT statements.
	SET NOCOUNT ON;
    delete from dbo.student where dbo.student.class not in (select class from dbo.class)
    -- Insert statements for trigger here
END

此觸發器的功能是:當class表有刪除操作時,同步student表中的記錄,將不存在的班級的記錄全部刪除.

使用觸發器：

altertable student drop CONSTRAINT  FK_CLASS
select* From student where class='chuyi'
select* From class where class='chuyi'
deletefrom class where class='chuyi'
select* From student where class='chuyi'
select* From class where class='chuyi‘
可以看到student表中的記錄也被更新了.

修改觸發器

set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go
ALTER TRIGGER  [trigger_1] 
   ON  [dbo].[class]
   AFTER DELETE
AS 
BEGIN
	-- SET NOCOUNT ON added to prevent extra result sets from
	-- interfering with SELECT statements.
	SET NOCOUNT ON;
    delete from dbo.student where dbo.student.class not in (select class from dbo.class)
    -- Insert statements for trigger here

END

刪除觸發器:Drop trigger trigger_1