个人笔记，仅供参考
查询练习数据准备
准备数据供下文使用
1、学生表(student)
学号，姓名，性别，出生年月日，班级
mysql> create table student(
-> sno varchar(20) primary key,
-> sname varchar(20) not null,
-> ssex varchar(20) not null,
-> sbirthday datetime,
-> class varchar(20)
-> );
2、课程表(course)
课程号，课程名称，教师编号
mysql> create table course(
-> cno varchar(20) primary key,
-> cname varchar(20) not null,
-> tno varchar(20) not null,
-> foreign key(tno) references teacher(tno)
-> );
3、成绩表(score)
学号，课程号，成绩
mysql> create table score(
-> sno varchar(20) not null,
-> cno varchar(20) not null,
-> degree decimal,
-> foreign key(sno) references student(sno),
-> foreign key(cno) references course(cno),
-> primary key(sno,cno)
-> );
4、教师表(teacher)
教师编号，教师姓名。教师性别，出生年月日，职称，所在部门
mysql> create table teacher(
-> tno varchar(20) primary key,
-> tname varchar(20) not null,
-> tsex varchar(10) not null,
-> tbirthday datetime,
-> prof varchar(20) not null,
-> depart varchar(20) not null
-> );
往数据表中添加数据
1、在学生表中添加以下数据
insert into student values('188','曾华','男','1997-09-01','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');
2、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');
3、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');
4、成绩表
insert into score values('103','3-245','86');
insert into score values('105','3-245','75');
insert into score values('109','3-245','68');
insert into score values('103','3-105','92');
insert into score values('105','3-105','88');
insert into score values('109','3-105','76');
insert into score values('103','6-166','85');
insert into score values('105','6-166','79');
insert into score values('109','6-166','81');
查询练习
1、查询student表的所有信息
select * from student;
2、查询student表中的所有记录的sname，ssex和class列
select sname, ssex, class from student;
3、查询教师所有的单位，即不重复的depart列
select distinct depart from teacher;
4、查询score表中成绩在60到80之间的所有记录
使用between...and...
select * from score where degree between 60 and 80;
或者使用运算符
select * from score where degree > 60 and degree < 80;
5、查询score表中成绩为85、86或88的记录
表示或者关系，in
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
使用or
select * from student where class='95031' or ssex='女';
7、以class降序查询student表的所有记录
升序(asc)，降序(desc) 默认为升序
select * from student order by class desc;
8、以con升序、degree降序查询score表的所有记录
即以cno升序排列，遇到相同的再以degree降序排列
select * from score order by cno asc,degree desc;
9、查询“95031”班的学生人数
统计count
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。（子查询或排序）
select sno,cno from score where degree=(select max(degree) from score);