[stanford]Introduction to databases (week3) 汇报贴！

This my work, so busy this week.
Does anyone know how to solve Movie-rating core set Q6 and social-network Mod Q3???

企盼黎明~ 发表于 2014-2-3 03:59
This my work, so busy this week.
Does anyone know how to solve Movie-rating core set Q6 and social- ...

过了好久了==我都有点遗忘了，我直接把我写的贴上来了，你看下哪里不懂再跟我说？

欢迎其他同学看看，SQL可以写的很简单，也可以写的很复杂……我算写的复杂的了=。=

Movie-rating core set Q6
select name, title
from Movie, Reviewer, Rating R1, Rating R2
where Movie.mID=R1.mID and R1.rID=Reviewer.rID and R2.rID=Reviewer.rID and R2.mID = Movie.mID
      and R1.stars<R2.stars
      and R1.ratingDate<R2.ratingDate

social-network Mod Q3
insert into Friend
select distinct F1.ID1, F2.ID2
from Friend F1, Friend F2
where F1.ID2=F2.ID1 and F1.ID1 <> F2.ID2
      and F1.ID1 not in (select F3.ID1 from Friend F3 where F3.ID2=F2.ID2);

这一周的完成了，3月的先留着。学校课程有点多

拖到今天...终于把sql的补上了 - -