Sql Server 触发器实例

最新推荐文章于 2023-08-04 08:33:06 发布

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最新推荐文章于 2023-08-04 08:33:06 发布

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五﹕使用T-SQL语句来创建触发器

基本语句如下﹕
           create trigger trigger_name
           on {table_name | view_name}
           {for | After | Instead of }
           [ insert, update,delete ]
           as
           sql_statement

六﹕相关示例﹕
1﹕在Orders表中建立触发器﹐当向Orders表中插入一条订单记录时﹐检查goods表的货品状态status是否为1(正在整理)﹐是﹐则不能往Orders表加入该订单。
create trigger orderinsert
on orders
after insert
as
if (select status from goods,inserted
where goods.name=inserted.goodsname)=1
begin
print 'the goods is being processed'
print 'the order cannot be committed'
rollback transaction   --回滚﹐避免加入
end
2﹕在Orders表建立一个插入触发器﹐在添加一条订单时﹐减少Goods表相应的货品记录中的库存。
create trigger orderinsert1
on orders
after insert
as
update goods set storage=storage-inserted.quantity
from goods,inserted
where
goods.name=inserted.goodsname
3﹕在Goods表建立删除触发器﹐实现Goods表和Orders表的级联删除。
create trigger goodsdelete
on goods
after delete
as
delete from orders
where goodsname in
(select name from deleted)
4﹕在Orders表建立一个更新触发器﹐监视Orders表的订单日期(OrderDate)列﹐使其不能手工修改.
create trigger orderdateupdate
on orders
after update
as
if update(orderdate)
begin
raiserror(' orderdate cannot be modified',10,1)
rollback transaction
end
5﹕在Orders表建立一个插入触发器﹐保证向Orders表插入的货品名必须要在Goods表中一定存在。
create trigger orderinsert3
on orders
after insert
as
if (select count(*) from goods,inserted where goods.name=inserted.goodsname)=0
begin
print ' no entry in goods for this order'
rollback transaction
end

6. 这两张表中的course相关联，我需要修改depart_course表中的course数据时，course表能够自动更新

例如：depart_course表中的course字段有一个是计算机原理，而course表中也有计算机原理这门课程的相关信息，也同样放在course表中的course字段

CREATE TRIGGER up ON depart_course
FOR UPDATE
AS

if Update(course)
begin
Update course
Set course=i.course
From course, Deleted d ,Inserted i
Where course.course=d.course

end