sql练习

建表 --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`) ); --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`) ); --教师表 CREATE TABLE `Teacher`( `t_id` VARCHAR(20), `t_name` VARCHAR(20) NOT NULL DEFAULT ‘‘, PRIMARY KEY(`t_id`) ); --成绩表 CREATE TABLE `Score`( `s_id` VARCHAR(20), `c_id` VARCHAR(20), `s_score` INT(3), PRIMARY KEY(`s_id`,`c_id`) ); --插入学生表测试数据 insert into Student values(‘01‘ , ‘赵雷‘ , ‘1990-01-01‘ , ‘男‘); insert into Student values(‘02‘ , ‘钱电‘ , ‘1990-12-21‘ , ‘男‘); insert into Student values(‘03‘ , ‘孙风‘ , ‘1990-05-20‘ , ‘男‘); insert into Student values(‘04‘ , ‘李云‘ , ‘1990-08-06‘ , ‘男‘); insert into Student values(‘05‘ , ‘周梅‘ , ‘1991-12-01‘ , ‘女‘); insert into Student values(‘06‘ , ‘吴兰‘ , ‘1992-03-01‘ , ‘女‘); insert into Student values(‘07‘ , ‘郑竹‘ , ‘1989-07-01‘ , ‘女‘); insert into Student values(‘08‘ , ‘王菊‘ , ‘1990-01-20‘ , ‘女‘); --课程表测试数据 insert into Course values(‘01‘ , ‘语文‘ , ‘02‘); insert into Course values(‘02‘ , ‘数学‘ , ‘01‘); insert into Course values(‘03‘ , ‘英语‘ , ‘03‘); --教师表测试数据 insert into Teacher values(‘01‘ , ‘张三‘); insert into Teacher values(‘02‘ , ‘李四‘); insert into Teacher values(‘03‘ , ‘王五‘); --成绩表测试数据 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);

 

练习题和sql语句

#1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数

select a.* ,b.s_score as 01_score,c.s_score as 02_score 
from student a 
join score b on a.s_id=b.s_id and b.c_id=‘01‘ 
left join score c on a.s_id = c.s_id and c.c_id = ‘02‘
where b.s_score > c.s_score;

或者：

select a.*,b.s_score as 01_score,c.s_score as 02_score 
from student a,score b,score c 
where a.s_id=b.s_id 
and a.s_id=c.s_id 
and b.c_id=‘01‘ 
and c.c_id=‘02‘ 
and b.s_score>c.s_score

 

#查询平均成绩小于60分的同学和没有成绩的的学生编号和学生姓名和平均成绩

select a.s_id,a.s_name,round(avg(b.s_score),2) as avg_score 
from student a
left join score b on a.s_id = b.s_id
group by a.s_id,a.s_name
having avg_score < 60 or avg_score is null

 

 

 

 

 

 

#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 a.s_id,a.s_name,round(avg(b.s_score),2) as avg_score 
from student a
left join score b on a.s_id = b.s_id
group by a.s_id,a.s_name
having avg_score >=60

 

#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 total_course,sum(b.s_score) as total_score
from student a
left join score b on a.s_id = b.s_id
group by a.s_id,a.s_name

 

#查询"李"姓老师的数量

#

 

 

select count(t.t_id) from teacher t
where t.t_name like ‘李%‘

 

#查询学过"张三"老师授课的同学的信息

select a.*
from student a
inner join score b on a.s_id = b.s_id
where b.c_id in(
    select c_id from course where t_id = (
        select t_id from teacher where t_name = ‘张三‘
    )
)

 

#

#查询没学过"张三"老师授课的同学的信息

select * from student c 
where c.s_id not in( 
    select a.s_id from student a 
    join score b on a.s_id=b.s_id 
    where b.c_id in( 
        select a.c_id from course a 
        join teacher b on a.t_id = b.t_id 
        where t_name =‘张三‘
    )
);

 

#查询学过编号为"01"并且也学过编号为"02"的课程的同学的信息

select a.* from student a
inner join score b on a.s_id = b.s_id
inner join score c on a.s_id = c.s_id
where b.c_id = ‘01‘
and c.c_id = ‘02‘;

或者

select a.* from 
student a,score b,score c 
where a.s_id = b.s_id  
and a.s_id = c.s_id 
and b.c_id=‘01‘ 
and c.c_id=‘02‘;

 

#查询学过编号为"01"但是没有学过编号为"02"的课程的同学的信息

select * from student 
where s_id in (select s_id from score where c_id=‘01‘)
and s_id not in (select s_id from score where c_id=‘02‘)

 

#查询没有学全所有课程的同学的信息

select a.* from student a
left join score b on a.s_id = b.s_id
group by a.s_id
having count(b.s_id) < (select count(c_id) from course);

 

#查询至少有一门课与学号为"01"的同学所学相同的同学的信息

select a.* from student a
inner join score b on a.s_id = b.s_id
where b.c_id in (
    select c_id from score where s_id =‘01‘
)
group by a.s_id;

 

#查询和"01"号的同学学习的课程完全相同的其他同学的信息

select a.* from student a
inner join score b on a.s_id = b.s_id
where a.s_id <> ‘01‘
group by b.s_id
having group_concat(b.c_id ORDER BY c_id) = 
    (
        select group_concat(c_id ORDER BY c_id) 
        from score where s_id = ‘01‘
    );

 

#

 

 

 

 

 

 

 

转自：https://blog.csdn.net/fashion2014/article/details/78826299

sql练习

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