第3章课堂综合练习题答案(1).ppt

1、An Introduction to Database System,第三章 综合练习,设有三个关系： S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher) 试用SQL语句表示下列查询语句,3、查询学号为S3学生所学课程的课程名与任课教师名 4、查询至少选修LIU老师所授课程中一门课程的女学生姓名 5、查询WANG同学不学的课程的课程号 6、查询至少选修两门课的学生学号 7、查询全部学生都选修的课程的课程号与课程名 8、查询选修课程包含LIU老师所授全部课程的学生学号。,1、查询LIU老师所授课程的课程号和课程名 2、查询年龄大

2、于23岁的男学生的学号和姓名,An Introduction to Database System,第三章 综合练习,设有三个关系： S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher) 试用SQL语句表示下列查询语句,10、求LIU老师所授课程的每门课程的平均成绩 11、检索姓名以L打头的所有学生的姓名和年龄。 12、求年龄大于所有女同学年龄的男学生姓名和年龄。 13、往关系C中插一个课程元组（C8,VC+,BAO） 14、把选修LIU老师课程的女同学选课元组全部删去。 15、把低于所有课程总平均成绩的男同学成绩提高5% .,

3、9、统计每门课程的学生选修人数（超过10人的课程才统计）。要求显示课程号和人数，查询结果按人数降序排列，若人数相同，按课程号升序排列。,An Introduction to Database System,综合练习答案,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),1、查询LIU老师所授课程的课程号和课程名,方法一： Select cno,cname from C where teacher=LIU,涉及到的表： C(cno,cname,teacher),方法二：LIKE Select cno,cname from C

4、where teacher like LIU,方法三：IN Select cno,cname from C where teacher in (LIU),An Introduction to Database System,综合练习答案,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),2、查询年龄大于23岁的男学生的学号和姓名,Select sno,sname from S where age23 and sex=M,涉及到的表：S(sno,sname,sex,age),方法一：一般的查询,An Introduction

5、to Database System,综合练习答案,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),2、查询年龄大于23岁的男学生的学号和姓名,Select sno,sname from S where age23 and sno in (select sno from s where sex=男),涉及到的表： S(sno,sname,sex,age),方法二：用IN嵌套查询,An Introduction to Database System,综合练习答案,S(sno,sname,sex,age) SC(sno,cno

6、,grade) C(cno,cname,teacher),2、查询年龄大于23岁的男学生的学号和姓名,Select sno,sname from S where age23 and sno =ANY (select sno from s where sex=男),涉及到的表： S(sno,sname,sex,age),方法三：用=ANY嵌套查询,An Introduction to Database System,综合练习答案,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),2、查询年龄大于23岁的男学生的学号和姓名,Se

7、lect sx.sno, sx.sname from s sx, s xy where sx.sno=sy.sno and sx.age23 and sy.sex=男,涉及到的表： Sx(sno,sname,sex,age),方法四：自连接,涉及到的表： Sy(sno,sname,sex,age),An Introduction to Database System,综合练习答案,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),2、查询年龄大于23岁的男学生的学号和姓名,Select sx.sno, sx.sname fr

8、om s sx inner join s xy on sx.sno=sy.sno where sx.age23 and sy.sex=男,涉及到的表： Sx(sno,sname,sex,age),方法五：内连接,涉及到的表： Sy(sno,sname,sex,age),An Introduction to Database System,综合练习答案,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),2、查询年龄大于23岁的男学生的学号和姓名,Select sx.sno, sx.sname from s sx where s

9、x.age23 and exists (select * from s sy where sy.sex=男 and sy.sno=sx.sno),涉及到的表： S(sno,sname,sex,age),方法六：用EXISTS嵌套查询,An Introduction to Database System,综合练习答案,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),2、查询年龄大于23岁的男学生的学号和姓名,Select sno,sname from S where age23 Intersect Select sno,sn

10、ame from S where sex=男,涉及到的表： S(sno,sname,sex,age),方法七：集合查询,An Introduction to Database System,综合练习答案,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),3、查询学号为S3学生所学课程的课程名与任课教师名,Select cname ,teacher from SC,C where SC.cno=C.cno and sno=S3,涉及到的表： SC(sno,cno,grade) C(cno,cname,teacher),方法一：

11、自然连接查询,An Introduction to Database System,综合练习答案,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),3、查询学号为S3学生所学课程的课程名与任课教师名,Select cname ,teacher From SC inner join C On SC.cno=C.cno where sno=S3,涉及到的表： SC(sno,cno,grade) C(cno,cname,teacher),方法二：内连接查询,An Introduction to Database System,综合

12、练习答案,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),3、查询学号为S3学生所学课程的课程名与任课教师名,Select cname ,teacher from C where cno in ( select cno from SC where sno=S3 ),涉及到的表： SC(sno,cno,grade) C(cno,cname,teacher),方法三：IN嵌套查询,An Introduction to Database System,综合练习答案,S(sno,sname,sex,age) SC(sno,cno,

13、grade) C(cno,cname,teacher),3、查询学号为S3学生所学课程的课程名与任课教师名,Select cname ,teacher from C where cno =ANY ( select cno from SC where sno=S3 ),涉及到的表： SC(sno,cno,grade) C(cno,cname,teacher),方法四：=ANY嵌套查询,An Introduction to Database System,综合练习答案,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),3、查询学

14、号为S3学生所学课程的课程名与任课教师名,Select cname ,teacher from C where exists (select * from SC where sno=S3 and SC.cno=C.cno),涉及到的表： SC(sno,cno,grade) C(cno,cname,teacher),方法五：EXIST嵌套查询,An Introduction to Database System,综合练习答案,4、查询至少选修LIU老师所授课程中一门课程的女学生姓名,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teache

15、r),Select sname from S,SC,C where S.sno=SC.sno and SC.cno=C.cno and sex=F and teacher=LIU,方法一：自然连接查询,涉及到全部的表：S，SC，C,An Introduction to Database System,综合练习答案,4、查询至少选修LIU老师所授课程中一门课程的女学生姓名,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),Select sname from S inner join SC On S.sno=SC.sno inn

16、er join C on SC.cno=C.cno where sex=F and teacher=LIU,方法二：内连接查询,涉及到全部的表：S，SC，C,An Introduction to Database System,综合练习答案,4、查询至少选修LIU老师所授课程中一门课程的女学生姓名,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),Select sname from S where sex=F and sno in (select sno from SC where cno in (select cno fr

17、om C where teacher=LIU),方法三：IN嵌套查询,涉及到全部的表：S，SC，C,An Introduction to Database System,综合练习答案,4、查询至少选修LIU老师所授课程中一门课程的女学生姓名,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),Select sname from S where sex=F and sno ANY (select sno from SC where cno =ANY (select cno from C where teacher=LIU),方法

18、四：ANY嵌套查询,涉及到全部的表：S，SC，C,An Introduction to Database System,综合练习答案,4、查询至少选修LIU老师所授课程中一门课程的女学生姓名,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),Select sname from S where sex=F and exists (select * from C where teacher=LIU and exists (select * from SC where SC.sno=S.sno and SC.cno=C.cno )

19、,方法五：EXISTS嵌套查询,涉及到全部的表：S，SC，C,An Introduction to Database System,综合练习答案,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),5、查询WANG同学不学的课程的课程号,Select cno from C where not exists (select * from S where sname=WANG and exists select * from SC where sno=SC.sno and cno=C.cno ),涉及到全部的表：S，SC，C,方法

20、一：NOT EXISTS嵌套查询,An Introduction to Database System,综合练习答案,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),5、查询WANG同学不学的课程的课程号,Select cno from C Where cno not in (select cno from SC where sno in (select sno from S where sname=WANG),涉及到全部的表：S，SC，C,方法二：NOT IN嵌套查询,An Introduction to Databas

21、e System,综合练习答案,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),5、查询WANG同学不学的课程的课程号,Select cno from C Where cno all (Select cno from SC where sno =any (select sno from S where sname=WANG),涉及到全部的表：S，SC，C,方法三：ANY/ALL查询,An Introduction to Database System,综合练习答案,S(sno,sname,sex,age) SC(sno,c

22、no,grade) C(cno,cname,teacher),5、查询WANG同学不学的课程的课程号,Select cno from C Minus Select distinct cno from S, SC where S.sno=SC.sno and sname=WANG,涉及到全部的表：S，SC，C,方法四：集合查询,An Introduction to Database System,综合练习答案,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),5、查询WANG同学不学的课程的课程号,Select cno fro

23、m C where not exists (select * from S,SC where S.sno=SC.sno and SC.cno=C.cno and sname=WANG),涉及到全部的表：S，SC，C,方法五：混合嵌套查询,An Introduction to Database System,综合练习答案,6、查询至少选修两门课的学生学号,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),Select sno from SC group by sno having count(*)=2,涉及到的表：SC,An

24、Introduction to Database System,综合练习答案,7、查询全部学生都选修的课程的课程号与课程名,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),Select cno,cname from C where not exists (select * from S where not exists (select * from SC where sno=S.sno and cno=C.cno),涉及到全部的表：S，SC，C,An Introduction to Database System,综合练习

25、答案,8、查询选修课程包含LIU老师所授全部课程的学生学号,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),Select distinct sno from SC as X where not exists (select * from C where teacher=LIU and not exists (select * from SC as Y where Y.sno=X.sno and Y.cno=C.cno),涉及到的表：SC，C,An Introduction to Database System,综合练习答案

26、,9、统计每门课程的学生选修人数（超过10人的课程才统计）。要求显示课程号和人数，查询结果按人数降序排列，若人数相同，按课程号升序排列,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),Select cno,count(sno) from SC group by cno having count(*)10 order by 2 desc,1,涉及到的表：SC,An Introduction to Database System,综合练习答案,10、求LIU老师所授课程的每门课程的平均成绩,S(sno,sname,sex,ag

27、e) SC(sno,cno,grade) C(cno,cname,teacher),Select C.cno,avg(grade) from SC,C where SC.cno=C.cno and teacher=LIU group by C.cno,涉及到的表：SC，C,An Introduction to Database System,综合练习答案,11、检索姓名以L打头的所有学生的姓名和年龄,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),Select sname,age from S where sname like L%,涉及到的表：S,An Introduction to Database System,综合练习答案,12、求年龄大于所有女同学年龄的男学生姓名和年龄,S(sno,sname,sex,age) SC(sno,cno,grade) C(cno,cname,teacher),Select sname,age from S where sex=M and a