实验四SQL进行复杂查询

select student.sno,sname,ssex,sage,sdept,cno,grade
from student,sc
where student.sno=sc.sno//?查询每个学生及其选课情况；

select first.cno,second.cpno
from course first,course second
where first.cpno=second.cno //?查询每门课的间接先修课

select student.sno,sname,ssex,sage,sdept,cno,grade
from student left outer join sc on student.sno=sc.sno//??将STUDENT,SC进行右连接

select student.sno,sname
from student inner join sc on student.sno=sc.sno
where cno=‘3‘ and sc.sno in
(select sno
from sc
where cno=‘2‘)//查询既选修了2号课程又选修了3号课程的学生姓名、学号；

select student.sno,sname
from student
where sname!=‘刘晨‘ and sage=
(select sage
from student
where sname=‘刘晨‘)//?查询和刘晨同一年龄的学生

select sname,sage
from student
where sno in
(select sno
from sc
where cno in
(select cno
from course
where cname=‘数据库‘))//?选修了课程名为“数据库”的学生姓名和年龄

select student.sno,sname
from student
where sdept<>‘IS‘ and
sage<all
(select sage
from student
where sdept=‘IS‘)//?查询其他系比IS系任一学生年龄小的学生名单

select student.sno,sname
from student
where sdept<>‘IS‘ and
sage<any
(select sage
from student
where sdept=‘IS‘)//?查询其他系中比IS系所有学生年龄都小的学生名单

select sname
from student
where Sno in
(select Sno from SC
group by Sno
having count(*) = (select count(*) from course ))//?查询选修了全部课程的学生姓名

select student.sno,sname
from student
where sdept=‘IS‘ and ssex=‘男‘//?查询计算机系学生及其性别是男的学生

select sno
from sc
where cno=‘1‘ except
select sno
from sc
where cno=‘2‘//?查询选修课程1的学生集合和选修2号课程学生集合的差集

select cno
from course
where cno not in
(select cno
from sc
where sno in
(select sno
from student
where sname=‘李勇‘))//?查询李勇同学不学的课程的课程号

select AVG(sage) as avgsage
from student inner join sc on student.sno=sc.sno
where cno=‘3‘//?查询选修了3号课程的学生平均年龄

select cno,AVG(grade) as avggrade
from sc
group by cno//求每门课程学生的平均成绩

select course.cno ‘课程号‘, count(sc.sno) ‘人数‘
from course,sc
where course.cno=sc.cno
group by course.cno having count(sc.sno)>3 order by COUNT(sc.sno) desc,course.cno asc//?统计每门课程的学生选修人数（超过3人的才统计）。要求输出课程号和选修人数，结果按人数降序排列，若人数相同，按课程号升序排列

select sname
from student
where sno>
(select sno from student where sname=‘刘晨‘)and
sage<(select sage from student where sname=‘刘晨‘)//?查询学号比刘晨大，而年龄比他小的学生姓名。

select sname,sage
from student
where ssex=‘男‘and sage>
(select MAX(sage) from student where ssex=‘女‘)//?求年龄大于所有女同学年龄的男同学姓名和年龄