针对书上的学生选课数据库S_T,用关系代数和SQL语言完成以下查询:
1、查询“ CS系所有学生的学号和姓名。

2、Slelect sno,sname from student where sdept = ' CS
3、查询所有姓“刘”的学生的信息。

4、Select * from stude nt where sn ame like '刘%
5、查询年龄在18至20岁之间的学生信息。

6、Select * from stude nt where sage betwee n 18 and 20
7、查询不在“ CS系也不在“ MA系的学生的所有信息。

& Select * from student where sdept not in ( ‘ CS , ' MA )
9、查询“ CS系所有学生的平均年龄。

10、Select avg(sage) from stude nt where sdept like ‘ CS
11、查询课程名是以“系统”结尾的课程信息。

12、Select * from course where cn ame like ‘ ％系统'
13、查询先行课为“ 6”号课程的课程信息。

14、Select * from course where cpno=6
15、查询间接先行课为“ 5”号课程的课程号及课程名。

16、Select , from c c1,c c2 where = and =5
17、Select eno ,cname from course where epno in (select eno from course where
epno=5)
18、查询没有先行课的课程名。

19、Select cn ame from course where epno is null
20、查询选修了“ 1”号课程的学生选课信息。

21、Select * from sc where eno=1
22、查询成绩为90分以上的学生姓名和课程名。

23、Select sn ame ,cn ame from s,c,sc where = and = and grade>=90
24、查询被选修了的课程号及课程名。

25、Select eno ,cn ame from course where eno in (Select disti nct(c no )
from sc)
26、Select eno ,cname from course where exists (select * from sc where
27、查询没有选修课程的学生学号及姓名。

28、Select sno,sname from s where sno not in (select distinct(sno) from sc)
29、Select sno ,sn ame from s where not exists(select * from sc where
30、查询没有选修“1”号课程的学生姓名。

31、Select sname from s where sno not in (select distinct(sno) from sc
where eno =1)
32、Select sn ame from s where not exists (select * from sc where = and
=1)
33、查询既选修了“数据结构”又选修了“操作系统”的学生姓名。

34、Select sn ame from ,sc where = and = and cn ame= ' 数据结构’
35、Select sname from s where sno in (select sno from sc where
eno=(slect eno from c where cname= 数据结构')and sno in (select sno from sc where eno=(select eno from c where en ame= '操作系
统’)))
36、Select snamefrom s where sno in (select sno from sc sc1,sc sc2 where =and
=(slect eno from c where ename= ' 数据结构’)and =(select eno from c
where en ame='操作系统’))
37、查询既选修了“ 2”号又选修了“ 4”号课程的学生学号。

38、Select sno from sc where eno=2 and sno in( select sno from sc where cno=4)
39、Select sno from sc sc1,sc sc2 where = and =2 and =4
40、查询选修了“ 2”号或“ 4”号课程的学生学号。

41、Select sno from sc where cno=2 or cno=4
42、查询至少选修了“ 95002”学生所选课程的学生学号。

43、Select from sc scx where not exists (select * from sc scy where
='95002' and not exists (select * from sc scz where = and =)
44、查询至少选修了一门其间接先行课为“ 7”号课程的学生姓名。

45、Select sn ame from s where sno in( Select sno from sc where eno in
(Select from c c1,c cl where = and =7))
46、查询选修了所有课程的学生姓名。

47、Select sn ame from s where not exists (select * from c where not
exists (select * from sc where = and =)
48、查询“李勇”同学所选课程的平均成绩。

49、Select avg(grade) from sc where sno =(Select sno from s where sname ='李
勇’)
50、查询“操作系统”这门课的最高分及最低分。

51、Select max(grade),m in( grade) from sc where eno=(select eno from
course where cn ame ='操作系统’)
52、查询“数据结构”这门课的选课人数。

53、Select coun t(s no) from sc where eno =(select eno from course where
cn ame=数据结构’)
54、查询“ CS系的所有学生的学号、姓名、课程名及成绩。

55、Select sno,sn ame,c name,grade from s,sc,c where = and = and sdept= ' CS
56、查询“ CS系选修课程的成绩在90分以上的所有女生的姓名、课程名和成
绩。

57、Select sname,cname,grade from s,sc,c where = and = and sdept= ' CS and
grade >=90 and ssex like '女'。