SQL数据库666666

Question

USE studentdb
go
SET NOCOUNT ON
go
--********** create trigger_insert_score --
-- Begin **********--

create trigger trigger_insert_score
on score
after insert
as
begin
if not exists
(select*
from student
where sno in(
select sno
from inserted))
begin
rollback transaction
begin transaction
end
end
--********** End --
go
delete from score
go
insert into score values('1001','2001','89.5')
go
insert into score values('1002','2001','95')
go
insert into score values('1011','2001','88')
go
select * from score
go
-- create trigger_delete_student --
-- Begin **********--

create trigger trigger_delete_student
on student
for delete
as
begin
delete from score
where sno in(
select sno
from deleted)

end
--********** End --
go
delete from student where sno='1001'
go
select * from score
go
-- create trigger_protect_grade --
-- Begin **********--

create trigger trigger_protect_grade
on score
for update
as
begin
rollback transaction
begin transaction
end
--********** End **********--
go
Update score set cno = 2021,grade = 99.0 where sno = '1002';
go
select * from score
go