设有一数据库，包括四个表：学生表（Student）、课程表（Course）、成绩表（Score）以及教师信息表（Teacher）。四个表的结构分别如表1-1的表（一）~表（四）所示，数据如表1-2的表（一）~表（四）所示。用SQL语句创建四个表并完成相关题目。

                 表1-1数据库的表结构

表（一）Student (学生表)                        

 表（二）Course（课程表）

表（三）Score(成绩表)

表（四）Teacher(教师表)

表1-2数据库中的数据

表（一）Student

 表（二）Course

表（三）Score

表（四）Teacher

1、查询Student表中的所有记录的Sname、Ssex和Class列。

select Sname,Ssex,Class from Student 

2、查询教师所有的单位即不重复的Depart列。

select distinct depart from Teacher

3、查询Student表的所有记录。

select * from student

4、 查询Score表中成绩在60到80之间的所有记录。

select * from score where degree btween 60 and 80

5、查询Score表中成绩为85，86或88的记录。

select * from score where degree in(85,86,88)

6、 查询Student表中“95031”班或性别为“女”的同学记录。

select * from student where class=‘95031‘ or ssex=‘女‘

7、 以Class降序查询Student表的所有记录。

select * from student order by class desc

8、 以Cno升序、Degree降序查询Score表的所有记录。

select * from score order by cno,degree desc

9、 查询“95031”班的学生人数。

select count(*) from student where class=‘95031‘

10、 查询Score表中的最高分的学生学号和课程号。（子查询或者排序）

select sno,cno from score where degree=(select max(degree) from score)
select * from score order by degree desc limit 0,1

11、 查询每门课的平均成绩。 

select cno,avg(degree) from score group by cno

12、查询Score表中至少有5名学生选修的并以3开头的课程的平均分数。

select avg(degree) from score where cno like‘3%‘ and cno in(select cno from score group by cno having count(*)>4)

select avg(degree) from score group by cno having count(*)>4 and cno like ‘3%‘

13、查询分数大于70，小于90的Sno列。

select sno from score where degree>70 and degree<90

14、查询所有学生的Sname、Cno和Degree列。

select student.sname,score.cno,score.degree from student,score where student.sno = score.sno

15、查询所有学生的Sno、Cname和Degree列。

select score.sno,course.cname,score.degree from score,course where score.cno=course.cno

16、查询所有学生的Sname、Cname和Degree列。

select student.sname,course.cname,degree from score,student,course where student.sno=score.sno and score.cno=course.cno

17、 查询“95033”班学生的平均分。

select avg(degree) from score where sno in(select sno from student where class=‘95033‘)

18、 假设使用如下命令建立了一个grade表：

create table grade(low  number(3),upp  number (3),rank  char(1))

insert into grade values(90,100,’A’)

insert into grade values(80,89,’B’)

insert into grade values(70,79,’C’)

insert into grade values(60,69,’D’)

insert into grade values(0,59,’E’)

现查询所有同学的Sno、Cno和rank列。

select sno,cno,rank from score,grade where degree between low and upp

19、  查询选修“3-105”课程的成绩高于“109”号同学成绩的所有同学的记录。

(1)select * from score where cno = ‘3-105‘ and degree>(select max(degree) from score where sno=‘109‘)
(2)select * from score where cno = ‘3-105‘ and degree>(select max(degree) from score where sno=‘109‘ and cno=‘3-105‘)

20、查询score中选学多门课程的同学中分数为非最高分成绩的记录。

(1)select * from score where sno in(select sno from score group by sno having count(*)>1) and degree<(select max(degree) from score)

(2)select * from score a where sno in(select sno from score group by sno having count(*)>1) and degree<(select max(degree) from score b where b.cno = a.cno)

21、查询成绩高于学号为“109”、课程号为“3-105”的成绩的所有记录。

select * from score where degree>(select degree from score where sno=‘109‘ and cno=‘3-105‘)

22、查询和学号为108的同学同年出生的所有学生的Sno、Sname和Sbirthday列。

select sno,sname,sbirthday from student where YEAR(sbirthday) = (select YEAR(sbirthday) from student where sno=‘108‘)

23、查询“张旭“教师任课的学生成绩。

select * from score where cno in(select cno from course where tno =(select tno from teacher where tname=‘张旭‘))

24、查询选修某课程的同学人数多于5人的教师姓名。

select tname from teacher where tno in(select tno from course where cno in(select cno from score group by cno having count(*)>5))

25、查询95033班和95031班全体学生的记录。

select * from student where class in(‘95033‘,‘95031‘)

26、  查询存在有85分以上成绩的课程Cno.

select distinct cno from score where degree>85

27、查询出“计算机系“教师所教课程的成绩表。

select * from score where cno in(select cno from course where tno in(select tno from teacher where depart=‘计算机系‘))

28、查询“计算机系”与“电子工程系“不同职称的教师的Tname和Prof。

select tname,prof from teacher where depart=‘计算机系‘ and prof not in(select prof from teacher where depart=‘电子工程系‘)
union
select tname,prof from teacher where depart=‘电子工程系‘ and prof not in(select prof from teacher where depart=‘计算机系‘)

select tname,prof from teacher where prof not in( select prof from teacher where depart=‘计算机系‘ and prof in(select prof from teacher where depart=‘电子工程系‘))

10月20日上午SQl数据库作业解析