create trigger deltable
on 訂購表
for delete
as
declare @ordnum int
select @ordnum=count(*) from 定單明細表, deleted i where 定單明細表.定單號=i.定單號
begin
 if(@ordnum>100)/*拒絕刪除*/
  begin 
  raiserror('拒絕刪除!',15,1)
  rollback transaction
  end
 if(@ordnum<10)/*級聯刪除*/
  begin 
  delete from  定單明細表 where 定單號=(select 定單號 from deleted)
  end
/*空值刪除*/
if(@ordnum>=10 and @ordnum<=100)
begin
update 定單明細表
set 定單號=null where 定單號=(select 定單號 from deleted)
end
end