MySQL强化练习答案
1、题目
题目：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。
2、数据库的表结构
2.1、表1：Student (学生表)
1 create table student 2 ( 3 sno varchar(20) not null primary key, 4 sname varchar(20) not null, 5 ssex varchar(20) not null, 6 sbirthday datetime, 7 class varchar(20) 8 );
2.2、表2：Teacher(教师表)
1 create table teacher 2 ( 3 tno varchar(20) not null primary key, 4 tname varchar(20) not null, 5 tsex varchar(20) not null, 6 tbirthday datetime, 7 prof varchar(20), 8 depart varchar(20) not null 9 );
2.3、表3：Course（课程表）
1 create table course 2 ( 3 cno varchar(20) not null primary key, 4 cname varchar(20) not null, 5 tno varchar(20) not null, 6 foreign key(tno) references teacher(tno) 7 );
2.4、表4：Score(成绩表)
1 create table score 2 ( 3 sno varchar(20) not null, 4 foreign key(sno) references student(sno), 5 cno varchar(20) not null, 6 foreign key(cno) references course(cno), 7 degree decimal 8 );
3、数据库中的数据
3.1、Student(学生表)
1 insert into student values('108','曾华','男','1977-09-01','95033'); 2 insert into student values('105','匡明','男','1975-10-02','95031'); 3 insert into student values('107','王丽','女','1976-01-23','95033'); 4 insert into student values('101','李军','男','1976-02-20','95033'); 5 insert into student values('109','王芳','女','1975-02-10','95031'); 6 insert into student values('103','陆君','男','1974-06-03','95031');
3.2、Teacher(教师表)
insert into teacher values (804,'李成','男','1958-12-2','副教授','计算机系'); insert into teacher values (856,'张旭','男','1969-3-12','讲师','电子工程系'); insert into teacher values (825,'王萍','女','1972-5-5','助教','计算机系');
insert into teacher values (831,'刘冰','女','1977-8-14','助教','电子工程系');
3.3、Course(课程表)
1 insert into course values('3-105','计算机导论','825'); 2 insert into course values('3-245','操作系统','804'); 3 insert into course values('6-166','数字电路','856'); 4 insert into course values('9-888','高等数学','831');
3.4、Score(成绩表)
1 insert into score values('103','3-245','86'); 2 insert into score values('105','3-245','75'); 3 insert into score values('109','3-245','68'); 4 insert into score values('103','3-105','92'); 5 insert into score values('105','3-105','88'); 6 insert into score values('109','3-105','76'); 7 insert into score values('103','3-105','64'); 8 insert into score values('105','3-105','91'); 9 insert into score values('109','3-105','78'); 10 insert into score values('103','6-166','85'); 11 insert into score values('105','6-166','79'); 12 insert into score values('109','6-166','81');
4、45小题答案
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
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 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）查询语句查询出一个或者一列结果，可以作为其他查询语句的参数来使用，就是子查询，就是查询的嵌套。
select Sno,Cno from Score where Degree=(select max(Degree) from Score) select Sno,Cno from Score order by Degree desc limit 0,1
11、查询每门课的平均成绩，要按照课程分组group by，然后求没门课平均avg
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。Like模糊查询 3%以3开头 having只能跟在group by 后面
SELECT AVG(Degree) FROM score where Cno LIKE '3%' GROUP BY Cno HAVING count(1)>5
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 Sname, Cno,Degree from Score , student where Score.Sno=student.Sno
15、查询所有学生的Sno、Cname和Degree列。
select Sno,Cname,Degree from Score , Course where Score.Cno=Course.Cno
16、查询所有学生的Sname、Cname和Degree列。
select Sname,Cname,Degree from student,course,score where student.Sno=score.Sno and course.Cno=score.Cno select Sname,Cname,Degree from student join score on student.Sno=score.Sno join course on course.Cno=score.Cno
17、 查询“95033”班学生的平均分。
select avg(degree) as 'class=95033' 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 int(3),upp int(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。
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。
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m绩的所有记录。
Select * from score where degree>(select degree from Score where Sno='109' and Cno='3-105' order by degree desc limit 1 )
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') select sno,sname,sbirthday from student where year(sbirthday) = (select year(sbirthday) from student where sno='101')
23、查询“张旭“教师任的学生成绩。
select Sno,degree from score,Course where score.Cno=Course.Cno and Course.Tno= (select Tno from Teacher where Tname='张旭' ) select degree 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, Course where Teacher.Tno=Course.Tno and Course.Cno =(select Cno from Score group by Cno having count(*)>5) select Tname from Teacher where tno=( select Tno from Course where cno=( 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 where degree>85
27、查询出“计算机系“教师所教课程的成绩表。
select * from course 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')
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')
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
select Cno,Sno,Degree 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 Cno,Sno,Degree from score where cno='3-105' and degree >all(select degree from score where cno='3-245' ) order by degree desc
31、 查询所有教师和同学的name、sex和birthday.
select tname,tsex,tbirthday from Teacher union select sname,ssex,sbirthday from Student
32、查询所有“女”教师和“女”同学的name、sex和birthday.
select Tname,Tsex,Tbirthday from Teacher where Tsex='女' union select Sname,Ssex,Sbirthday from Student where Ssex='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 b.cno=a.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 )
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 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(*)>1
37.查询不姓王的同学信息
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) 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 * from Student order by class desc, Sbirthday
41、查询“男”教师及其所上的课程。
select Tname,Cname from course,teacher where course.tno= teacher.tno and teacher.Tsex='男'
42、查询最高分同学的Sno、Cno和Degree列。
select Sno,Cno,Degree from score where degree=(select max(degree) from score) 排序写法：select Sno,Cno,Degree from score order by degree desc limit 0,1
43、查询所有选修“计算机导论”课程的“男”同学的成绩表。
SELECT * from score JOIN course ON course.Cno=score.Cno AND Cname='计算机导论' join student ON student.Sno=score.Sno AND Ssex='男'
44、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')
45、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')
46、查询所有选修“计算机导论”课程的“男”同学的成绩表。
select Sno,Cno,degree from score where Cno=( select Cno from course where Cname='计算机导论') and Sno in (select Sno from student where Ssex='男')
