MySQL自测测试

#建学生信息表student
create table student
(
sno varchar(20) not null primary key,
sname varchar(20) not null,
ssex varchar(20) not null,
sbirthday datetime,
class varchar(20)

);
#建立教师表
create table teacher
(
tno varchar(20) not null primary key,
tname varchar(20) not null,
tsex varchar(20) not null,
tbirthday datetime,
prof varchar(20),
depart varchar(20) not null

);
#建立课程表course
create table course
(
cno varchar(20) not null primary key,
cname varchar(20) not null,
tno varchar(20) not null,
foreign key(tno) references teacher(tno)

);
#建立成绩表
create table score
(
id int auto_increment primary key,
sno varchar(20) not null,
foreign key(sno) references student(sno),
cno varchar(20) not null,
foreign key(cno) references course(cno),
degree decimal

);

#添加学生信息
insert into student values('108','曾华','男','1977-09-01','95033');
insert into student values('105','匡明','男','1975-10-02','95031');
insert into student values('107','王丽','女','1976-01-23','95033');
insert into student values('101','李军','男','1976-02-20','95033');
insert into student values('109','王芳','女','1975-02-10','95031');
insert into student values('103','陆君','男','1974-06-03','95031');




#添加教师表
insert into teacher values('804','李诚','男','1958-12-02','副教授','计算机系');
insert into teacher values('856','张旭','男','1969-03-12','讲师','电子工程系');
insert into teacher values('825','王萍','女','1972-05-05','助教','计算机系');
insert into teacher values('831','刘冰','女','1977-08-14','助教','电子工程系');

#添加课程表
insert into course values('3-105','计算机导论','825');
insert into course values('3-245','操作系统','804');
insert into course values('6-166','数字电路','856');
insert into course values('9-888','高等数学','831');
#添加成绩表

insert into score values(1,'103','3-245','86');
insert into score values(2,'105','3-245','75');
insert into score values(3,'109','3-245','68');
insert into score values(4,'103','3-105','92');
insert into score values(5,'105','3-105','88');
insert into score values(6,'109','3-105','76');
insert into score values(7,'103','3-105','64');
insert into score values(8,'105','3-105','91');
insert into score values(9,'109','3-105','78');
insert into score values(10,'103','6-166','85');
insert into score values(11,'105','6-166','79');
insert into score values(12,'109','6-166','81');


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；#distinct意思是过滤不重复的

4、 查询Score表中成绩在60到80之间的所有的学生记录。

select student.sname from score
left join student on student.sno=score.sno
where degree>60 and degree<81
group by student.sname

5、 查询Score表中成绩为85，86或88的学生记录

select student.sname from score
left join student on student.sno=score.sno
where Degree in(85,86,88)
group by student.sname

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; #desc 是降序所默认为升序

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 #asc为升序，默认为asc desc为降序 

14、     查询所有学生的Sname、Cno和Degree列。

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 cno,sno from score where degree=(select max(degree) from score);
select cno,sno from score order by degree desc limit 0,1; #limit 0,1 意思是区一行 0,2就是取二行

11、     查询每门课的平均成绩

 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

 select  avg(degree) from score where cno like '3%' and cno in(select cno from score group by cno having count(*)>=5);
#like 模糊查询里面包含3的

13  查询分数大于70，小于90的Sno列。

select sno from score where degree>70 and degree<90 group by sno;

14、     查询所有学生的Sname、Cno和Degree列。 

 

15、     查询所有学生的Sno、Cname和Degree列。