大题目 topic下面有0~N个question,
topic有个属性scores,每一个question下面也有scores。
topic.scores = sum(question.scores)
请问如何保证这一点:topic.scores = sum(question.scores)?
topic有个属性scores,每一个question下面也有scores。
topic.scores = sum(question.scores)
请问如何保证这一点:topic.scores = sum(question.scores)?
create trigger tig_question on question
for insert,update,delete
as
begin
if exists(select 1 from inserted) --添加或更新
begin
update topic set topic.scores=(select isnull(sum(scores),0) from question,inserted where question.topicid=inserted.topicid) from inserted where inserted.topicid=topic.topicid
end
if exists(select 1 from deleted)--删除情况
begin
update topic set topic.scores=(select isnull(sum(scores),0) from question,deleted where question.topicid=deleted.topicid) from deleted where deleted.topicid=topic.topicid
end
end