student:s
course:c
teacher:t
sc:sc1,sc2
先分别选语文的和数学的选修学生和分数
1、create
view
yuwen
as
select
sid,score
from
sc1,c
where
c.cid=sc1.cid
and
c.cname=‘语文'
2、create
view
shuxue
as
select
sid,score
from
sc2,c
where
c.cid=sc2.cid
and
c.cname=‘数学'
然后选出以上数据中同时选了两门课程且语文比数学成绩高的学生
3、create
view
student_id
as
select
yuwen.sid
from
yuwen,shuxue
where
yuwen.score>shuxue.score
and
yuwen.sid=shuxue.sid
选出语文成绩比数学成绩高的学生的sid:最后的结果语句就有了:
4、select
s.sname
from
s,student_id
where
s.sid
=
student_id
也可以这样写:
1、create
view
yuwen
as
select
sname,sc1.sid,score
from
s,sc1,c
where
s.sid
=sc1.sid
and
c.cid=sc1.cid
and
c.cname=‘语文'
2、create
view
shuxue
as
select
sname,
sc2.sid,score
from
sc2,c
where
c.cid=sc2.cid
and
c.cname=‘数学'
3、select
sname
from
(select
yuwen.sname
from
yuwen,shuxue
where
yuwen.score>shuxue.score
and
yuwen.sid=shuxue.sid)
以上是一个详细的分析过程。写在一个句子里的话句子结构就有点复杂了。希望网友们补齐啊。