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1-2数据库中的数据 ：
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 between 60 and 80 (where degree>=60 && degree <=80)
5、查询Score表中成绩为85，86或88的记录。
select * from score where degree==85||degree==86||degree==88 (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 studnt 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 asc, 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）
排序：select Sno,Cno from score order by degree desc limit 0,1
子查询：select Sno,Cno from score where degree=(select max (Degree) from score)
11、查询每门课的平均成绩。按照课程分组(group by)，查询每门课平均成绩
select 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。
查询以3开头的课程 select Cno from score where Cno like “3%”
查询至少有5名学生选修的课程号 select Cno from score group by Cno having count (*)>=5
select avg(degree),Cno from score where Cno in (selet Cno from score where Cno like "3%" group by Cno having count(*)>=5)
13、查询分数大于70，小于90的Sno列。
select Sno from score where degree>70 and degree (select 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
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 *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 Cno from score group by Cno having max(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 * 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'))
select * from teacher where prof in (select 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 * from teacher where prof in (select prof from teacher where depart ='电子工程系' and prof not in (select prof from teacher where depart='计算机系'))
29、查询选修编号为“3-105“课程且成绩至少高于选修编号为“3-245”的同学的Cno、Sno和Degree,并按Degree从高到低次序排序。
select * from score where Cno='3-105' and degree> any(select degree from score where Cno='3-245') order by degree desc
30、查询选修编号为“3-105”且成绩高于选修编号为“3-245”课程的同学的Cno、Sno和Degree.
Select * from score where Cno=’3-105’and degree> all (select degree from score where Cno=’3-245’)
31、 查询所有教师和同学的name、sex和birthday.
Select Sname, Ssex, Sbirthday from student union select Tname, Tsex, Tbirthday from teacher
32、查询所有“女”教师和“女”同学的name、sex和birthday.
Select Sname, Ssex, Sbirthday from student where Ssex='女' union select Tname, Tsex, Tbirthday from teacher where Tsex='女'
33、 查询成绩比该课程平均成绩低的同学的成绩表。
Select * from score a where degree< (select avg(degree) from score b where a.Cno=b.Cno)
34、 查询所有任课教师的Tname和Depart.
Select Tname, Depart from teacher where Tno in (Select Tno from course where Cno in (Select distinct Cno from score))
35 、 查询所有未讲课的教师的Tname和Depart.
Select Tname, depart from teacher where Tno not in (Select Tno from course where Cno in (Select distinct Cno from score))
36、查询至少有2名男生的班号。
Select Class from student where Ssex='男' group by Class having count(Ssex)>=2
37、查询Student表中不姓“王”的同学记录。
select * from student where Sname not like ‘王%’
38、查询Student表中每个学生的姓名和年龄。
Select Sname, year(now())-year(Sbirthday) as age from student
39、查询Student表中最大和最小的Sbirthday日期值。
select max(Sbirthday),min(Sbirthday) from student
40、以班号和年龄从大到小的顺序查询Student表中的全部记录。
Select Class,year(now())-year(Sbirthday) as age from student order by Class desc, age
41、查询“男”教师及其所上的课程。
Select Cname from course where Tno in (Select Tno from teacher where Tsex='男')
42、查询最高分同学的Sno、Cno和Degree列。
Select * from score order by degree desc limit0,1 select * from score where degree = (select max(degree) from score)
43、查询和“李军”同性别的所有同学的Sname.
Select Sname from student where Ssex=( Select Ssex from student where Sname='李军')
44、查询和“李军”同性别并同班的同学Sname.
Select Sname from student where Ssex=( Select Ssex from student where Sname='李军')and Class=( Select Class from student where Sname='李军')
45、查询所有选修“计算机导论”课程的“男”同学的成绩表。
Select * from score where Sno in (select Sno from student where Ssex='男') and Cno in (select Cno from course where Cname='计算机导论')