MySQL综合项目作业

目录

作业要求

基础配置

结果

作业要求

1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数

2、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

3、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

4、查询"李"姓老师的数量

5、查询学过"张三"老师授课的同学的信息

基础配置

创建名为mysql_exampleTest的库，并使用

create database mysql_exampleTest;
use mysql_exampleTest;

创建学生表

CREATE TABLE Student(
s_id VARCHAR(20),
s_name VARCHAR(20) NOT NULL DEFAULT '',
s_birth VARCHAR(20) NOT NULL DEFAULT '',
s_sex VARCHAR(10) NOT NULL DEFAULT '',
PRIMARY KEY(s_id)
)

插入学生表数据

insert into Student values('01' , 'zhaolei' , '1990-01-01' , 'man');
insert into Student values('02' , 'qiandian' , '1990-12-21' , 'man');
insert into Student values('03' , 'sunfeng' , '1990-05-20' , 'man');
insert into Student values('04' , 'liyun' , '1990-08-06' , 'man');
insert into Student values('05' , 'zhoumei' , '1991-12-01' , 'woman');
insert into Student values('06' , 'wulan' , '1992-03-01' , 'woman');
insert into Student values('07' , 'zengjv' , '1989-07-01' , 'woman');
insert into Student values('08' , 'wangjv' , '1990-01-20' , 'woman'); 

创建课程表

CREATE TABLE Course(
c_id VARCHAR(20),
c_name VARCHAR(20) NOT NULL DEFAULT '',
t_id VARCHAR(20) NOT NULL,
PRIMARY KEY(c_id)
);

插入课程表数据

 insert into Course values('01' , 'CHINESE' , '02');
insert into Course values('02' , 'MATH' , '01');
insert into Course values('03' , 'ENGLISH' , '03');

创建教师表

CREATE TABLE Teacher(
t_id VARCHAR(20),
t_name VARCHAR(20) NOT NULL DEFAULT '',
PRIMARY KEY(t_id)
);

插入教师表数据

insert into Teacher values('01' , 'zhangsan');
insert into Teacher values('02' , 'lisi');
insert into Teacher values('03' , 'wangwu'); 

创建成绩表

CREATE TABLE Score(
s_id VARCHAR(20),
c_id VARCHAR(20),
s_Score INT(3),
PRIMARY KEY(s_id,c_id)
)；

插入成绩表数据

 insert into Score values('01' , '01' , 80);
insert into Score values('01' , '02' , 90);
insert into Score values('01' , '03' , 99);
insert into Score values('02' , '01' , 70);
insert into Score values('02' , '02' , 60);
insert into Score values('02' , '03' , 80);
insert into Score values('03' , '01' , 80);
insert into Score values('03' , '02' , 80);
insert into Score values('03' , '03' , 80);
insert into Score values('04' , '01' , 50);
insert into Score values('04' , '02' , 30);
insert into Score values('04' , '03' , 20);
insert into Score values('05' , '01' , 76);
insert into Score values('05' , '02' , 87);
insert into Score values('06' , '01' , 31);
insert into Score values('06' , '03' , 34);
insert into Score values('07' , '02' , 89);
insert into Score values('07' , '03' , 98);

 结果

1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数

运行代码展示：

select st.*,sc.s_Score CHINESE' ,sc2.s_Score 'MATH' 
from Student st
left join Score sc on sc.s_id=st.s_id and sc.c_id='01' 
left join Score sc2 on sc2.s_id=st.s_id and sc2.c_id='02'  
where sc.s_Score>sc2.s_Score;

运行结果展示： 

 2、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

 运行代码展示：

select st.s_id,st.s_name,ROUND(AVG(sc.s_Score),2) cjScore from Student st
left join Score sc on sc.s_id=st.s_id
group by st.s_id having AVG(sc.s_Score)>=60;

 运行结果展示： 

 

 3、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

  运行代码展示：

select st.s_id,st.s_name,count(sc.c_id) '选课总数',(case when sum(sc.s_Score) is null or sum(sc.s_Score)='' then 0 else sum(sc.s_Score) end) '总成绩'
from Student st
left outer join Score sc on st.s_id=sc.s_id
group by st.s_id;

 运行结果展示：

 4、查询"李"姓老师的数量

  运行代码展示：

select t.t_name,count(t.t_id) from Teacher t
group by t.t_id having t.t_name like "li%"; 

  运行结果展示：

5、查询学过"张三"老师授课的同学的信息

运行代码展示：

select st.* from Student st 
left join Score sc on sc.s_id=st.s_id
left join Course c on c.c_id=sc.c_id
left join Teacher t on t.t_id=c.t_id
where t.t_name="zhangsan";

运行结果展示：