create trigger gra_update
on student?
for delete
as
declare @sname char(10)
select @sname=sno from deleted
if @sname='95001'
begin rollback transaction
print'95001不能被删除'
end
else
begin
?print @sname+'改条目已删除'
end
?
?
alter trigger gra_update
on student?
for delete
as
declare @sname char(10)
select @sname=sno from deleted
if @sname='95001'
begin rollback transaction
print'95001不能被删除'
end
else
begin
?print @sname+'改条目已删除'
end
?
删除触发器的建立]
?
delete from student where sno='95002'
删除1个条目
?
?
?
alter trigger gra_update1
on student
for update,insert,delete
as
declare @sname char(10)
declare @grade smallint
select @sname=sno,@grade=grade from student where grade>100 or grade<0?
if @grade<0
begin ?
update student set grade=0 where sno=@sname
print '成绩有误'+@sname+'成绩为零'
end
else if @grade>100
begin rollback transaction?
print'chengjiyouwu'+@sname+'成绩无效'
end
else?
begin
print'输入成绩有效 已经更新'
end
?
一个触发器 当输入成绩小于0的时候提示错误
当输入成绩大于100时 回滚 修改的成绩不变
?
?
update student set grade=108 where sno='95004'
修改95004的分数 输入108分 但是有触发器的管理
成绩为100 如下：
输入成绩有效 已经更新
?
（所影响的行数为 1 行）
?
95004 ? ? grade over 100
输入成绩有效 已经更新
?
（所影响的行数为 1 行）
?
create或
alter trigger sno_insert
on student
for insert
as
declare @sno char(10)
select @sno=sno from insered?
select @sno=count(sno) from student where sno=@sno
insert into tmp_insered values(@sno)
if @sno>1
begin
rollback transaction
print '数据无效'
end
?
