MYSQL笔试题（考试题）附带答案

表名和字段

• 1.学生表 
• Student(s_id,s_name,s_birth,s_sex) –学生编号,学生姓名, 出生年月,学生性别 
• 2.课程表 
• Course(c_id,c_name,t_id) – –课程编号, 课程名称, 教师编号 
• 3.教师表 
• Teacher(t_id,t_name) –教师编号,教师姓名 
• 4.成绩表 
• Score(s_id,c_id,s_score) –学生编号,课程编号,分数

建库建表：

创建数据库：

drop database if exists stu;
create database stu;

创建学生表：

create table student(
	s_id int(10) not null auto_increment comment '学生编号',
	s_name varchar(10) not null comment '学生姓名',
	s_birth varchar(20) not null comment '出生日期',
	s_sex varchar(2) not null comment '性别',
	primary key(s_id)
) engine=innodb  default charset=utf8;

创建课程表：

create table student(
	s_id int(10) not null auto_increment comment '学生编号',
	s_name varchar(10) not null comment '学生姓名',
	s_birth varchar(20) not null comment '出生日期',
	s_sex varchar(2) not null comment '性别',
	primary key(s_id)
) engine=innodb  default charset=utf8;

创建课程表：

create table course(
	c_id int(10) not null auto_increment comment '课程编号',
	c_name varchar(10) not null comment '课程名称',
	t_id int(10) not null comment '任课老师',
	primary key(c_id)

) engine=innodb default charset=utf8;

创建教师表：

create table teacher(
	t_id int(10) not null auto_increment comment '教师编号',
	t_name varchar(10) not null comment '教师姓名',
	primary key(t_id)
) engine=innodb default charset=utf8;

成绩表：

create table score(
	s_id int(10) not null auto_increment comment '成绩编号',
	c_id int(10) not null comment '课程编号',
	s_score int(3) not null comment '学生分数',
	primary key(s_id,c_id)
) engine=innodb default charset=utf8;

测试数据：

插入学生表测试数据 （学生编号，学生姓名，出生日期，性别）：

insert into Student values(1, '赵雷' , '1990-01-01' , '男');
insert into Student values(2, '钱电' , '1990-12-21' , '男');
insert into Student values(3, '孙风' , '1990-05-20' , '男');
insert into Student values(4, '李云' , '1990-08-06' , '男');
insert into Student values(5, '周梅' , '1991-12-01' , '女');
insert into Student values(6, '吴兰' , '1992-03-01' , '女');
insert into Student values(7, '郑竹' , '1989-07-01' , '女');
insert into Student values(8, '王菊' , '1990-01-20' , '女');

课程表测试数据        （课程编号，课程名，任课教师编号）：

insert into Course values(1, '语文' , 2);
insert into Course values(2, '数学' , 1);
insert into Course values(3, '英语' , 3);

教师表测试数据        （教师编号，教师名）：

insert into Teacher values(1 , '张三');
insert into Teacher values(2 , '李四');
insert into Teacher values(3 , '王五');

成绩表测试数据    （成绩编号，课程编号，成绩）

insert into Score values(1 , 1 , 80);
insert into Score values(1 , 2 , 90);
insert into Score values(1 , 3 , 99);
insert into Score values(2 , 1 , 70);
insert into Score values(2 , 2 , 60);
insert into Score values(2 , 3 , 80);
insert into Score values(3 , 1 , 80);
insert into Score values(3 , 2 , 80);
insert into Score values(3 , 3 , 80);
insert into Score values(4 , 1 , 50);
insert into Score values(4 , 2 , 30);
insert into Score values(4 , 3 , 20);
insert into Score values(5 , 1 , 76);
insert into Score values(5 , 2 , 87);
insert into Score values(6 , 1 , 31);
insert into Score values(6 , 3 , 34);
insert into Score values(7 , 2 , 89);
insert into Score values(7 , 3 , 98);

练习题、sql语句、执行结果：

--1.查询语文成绩比数学成绩高的学生的信息以及课程分数

select a.* , b.s_score as chinese , c.s_score as math from
student a 
join score b on b.c_id = 1 and a.s_id = b.s_id
left join score c on  c.c_id = 2 and a.s_id = c.s_id where b.s_score > c.s_score;

运行结果：

--2.查询语文成绩比数学成绩低的学生的信息以及课程分数

select a.* , b.s_score as chinese , c.s_score as math from
student a
join score b on b.c_id = 1 and a.s_id = b.s_id
left join score c on c.c_id = 2 and a.s_id = c.s_id
where b.s_score < c.s_score; 

运行结果：

--3.查询平均成绩大于等于60分的同学的学生编号和学生姓名和平均成绩

select b.s_id , b.s_name,round(avg(a.s_score),1) as avg_score
from student b
join score a on b.s_id = a.s_id
group by b.s_id,b.s_name having round(avg(a.s_score),1)>=60;

运行结果：

--4.查询平均成绩小于60分的同学编号和学生姓名和平均成绩（包括有成绩和没有成绩的）

select b.s_id,b.s_name,round(avg(a.s_score)) as avg_score 
from student b
left join score a on b.s_id = a.s_id
group by b.s_id,b.s_name having round(avg(a.s_score),2)<60
union
select a.s_id,a.s_name,0 as avg_score 
from student a 
where a.s_id not in (select distinct s_id from score);  

运行结果：

-- 5、查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩

select a.s_id,a.s_name,count(b.c_id) as sum_course,sum(b.s_score) as sum_score 
from student a
left join score b on a.s_id = b.s_id
group by a.s_id,a.s_name;

运行结果：