1.创建student和score表
Create table student(
Id int(10)not nullunique primary key,
Name Varchar(20) not null,
Sex varchar(4),
Birth year,
Department varchar(20),
Address varchar(50)
);
创建score表
create table score(
id int(10) not null unique primary keyauto_increment,
stu_id int(10) not null,
c_name varchar(20),
grade int(10)
);
2.为student 表和score 表增加记录
向student表中插入记录
Insert into student values(901,‘张老大’,‘男’,’1985‘,’计算机系’,‘北京市海淀区’);
Insert into student values(901,‘张老二’,‘男’,‘’1986‘,中文系,‘北京市昌平区’);
Insert into student values(901,‘张三’,‘男’,’1990‘, ‘中文系’,‘湖南省永州市’);
Insert into student values(901,‘李四’,‘男’,’1990‘, ‘英语系’,‘辽宁省阜新市’);
Insert into student values(901,‘王五’,‘男’,’1991, ‘英语系’,‘福建省厦门市’);
Insert into student values(901,‘王六’,‘男’,’1988‘, ‘计算机系’,‘湖南省衡阳市’);
向score表插入记录的语句
Insert into score values( null ,901,’计算机’,98);
Insert into score values( null ,901,’英语‘,80);
Insert into score values( null ,902,’计算机‘,65);
Insert into score values( null ,902,’中文,‘88);
Insert into score values( null ,903,’中文‘,95);
Insert into score values( null ,904,’计算机‘,70);
Insert into score values( null ,904,’英语‘,92);
Insert into score values( null ,905,’英语‘,94);
Insert into score values( null ,906,’计算机‘,90);
Insert into score values( null ,906,’英语,‘85);
3.查询student表的所有记录
select * from student;
4.查询student表的第2条到第4条的记录 关键词 limit
select * from student limit 1,3;
5.从student表查询所有学生的学号 、姓名和院系的信息
select id,name,department from student;
6.从student表中查询计算机系和英语系的学生的信息
select * from student where department in(‘计算机系’,‘英语系’);
7.从student表中查询年龄18-22岁的学生信息
select id,name ,sex,2013-birth as age,department,address from student where 2013-birth between 18 and 22;
select id,name,sex,2013-birth,department ,address from student where 2013-birth >= 18 and 2013-birth <= 22;
8.从student表中查询每个院系有多少人
select department,count(id) from student group by department;
9.从score表中查询每个科目的最高分
select c_name,Max(grade) from score group by c_name;
10.查询李四的考试科目(c_name)和考试成绩(grade)
select c_name,grade from score where stu_id = (select id from student where name = ‘李四’);
11.用链接的方式查询所有学生的信息和考试信息
select student.id, name , sex , birth ,department ,address,c_name,grade from student , score where student.id = score.stu_id;
12.计算每个学生的总成绩
select student.id ,name ,sum(grade) from student ,score where student.id = score.stu_id group by id;
13.计算每个考试科目的平均成绩
select c_name,avg(grade) from score group by c_name;
14.查询计算机成绩低于95的学生信息
select * from student where id in(select stu_id from score where c_name = '计算机’ and grade < 95);
15.查询同时参加计算机和英语考试的学生的信息
select * from student where id = any
(select stu_id from score where stu_id in
(select stu_id from score where c_name = '计算机' )
and c_name = '英语');
select a.* from student a ,score b,score c
where a.id = b.stu_id
and b.c_name ='计算机'
and a.id = c.stu_id
and c.c_name = '英语';
16.将计算机考试成绩按从高到低进行排序
select stu_id ,grade
from score where c_name = '计算机'
order by grade desc;
17.从student表和score表中查询出学生的学号,然后合并查询结果
select id from student union select stu_id from score;
18.查询姓张或者姓王的同学的姓名、院系和考试科目及成绩
select student.id ,name,sex,birth,department,address,c_name,grade
from student ,score
where
(name like '张%' or name like '王%')
and
student.id = score.stu_id;
19.查询都是湖南的学生的姓名、年龄、院系和考试科目及成绩
select student.id ,name,sex,birth,department,address,c_name ,grade,
from student,score
where address like '湖南%' and
student.id = score.stu_id;