1、表结构
–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
2、测试数据
--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
);
3、测试题
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' or c
.c_id
= NULL where b
.s_score
>c
.s_score
2、查询"01"课程比"02"课程成绩低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
left join score b
on a
.s_id
=b
.s_id
and b
.c_id
='01' or b
.c_id
=NULL
join score c
on a
.s_id
=c
.s_id
and c
.c_id
='02' where b
.s_score
<c
.s_score
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
),2) 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
),2)>=60;
4、查询平均成绩小于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
),2) 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
);
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
;
6、查询"李"姓老师的数量
select count(t_id
) from teacher
where t_name
like '李%';
7、查询学过"张三"老师授课的同学的信息
select a
.* from
student a
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'));
8、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 c_id
from course
where t_id
=(
select t_id
from teacher
where t_name
= '张三')));
9、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
,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';
10、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 a
.* from
student a
where a
.s_id
in (select s_id
from score
where c_id
='01' ) and a
.s_id
not in(select s_id
from score
where c_id
='02')
11、查询没有学全所有课程的同学的信息
select s
.* from
student s
where s
.s_id
in(
select s_id
from score
where s_id
not in(
select a
.s_id
from score a
join score b
on a
.s_id
= b
.s_id
and b
.c_id
='02'
join score c
on a
.s_id
= c
.s_id
and c
.c_id
='03'
where a
.c_id
='01'))
12、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 * from student
where s_id
in(
select distinct a
.s_id
from score a
where a
.c_id
in(select a
.c_id
from score a
where a
.s_id
='01')
);
13、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
where a
.s_id
in(
select distinct s_id
from score
where s_id
!='01' and c_id
in(select c_id
from score
where s_id
='01')
group by s_id
having count(1)=(select count(1) from score
where s_id
='01'));
14、查询没学过"张三"老师讲授的任一门课程的学生姓名
select a
.s_name
from student a
where a
.s_id
not in (
select s_id
from score
where c_id
=
(select c_id
from course
where t_id
=(
select t_id
from teacher
where t_name
= '张三'))
group by s_id
);
15、查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩
select a
.s_id
,a
.s_name
,ROUND(AVG(b
.s_score
)) from
student a
left join score b
on a
.s_id
= b
.s_id
where a
.s_id
in(
select s_id
from score
where s_score
<60 GROUP BY s_id
having count(1)>=2)
GROUP BY a
.s_id
,a
.s_name
16、检索"01"课程分数小于60，按分数降序排列的学生信息
select a
.*,b
.c_id
,b
.s_score
from
student a
,score b
where a
.s_id
= b
.s_id
and b
.c_id
='01' and b
.s_score
<60 ORDER BY b
.s_score
DESC;
17、按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩
select a
.s_id
,(select s_score
from score
where s_id
=a
.s_id
and c_id
='01') as 语文
,
(select s_score
from score
where s_id
=a
.s_id
and c_id
='02') as 数学
,
(select s_score
from score
where s_id
=a
.s_id
and c_id
='03') as 英语
,
round(avg(s_score
),2) as 平均分
from score a
GROUP BY a
.s_id
ORDER BY 平均分
DESC;
18.查询各科成绩最高分、最低分和平均分：以如下形式显示：课程ID，课程name，最高分，最低分，平均分，及格率，中等率，优良率，优秀率
select a
.c_id
,b
.c_name
,MAX(s_score
),MIN(s_score
),ROUND(AVG(s_score
),2),
ROUND(100*(SUM(case when a
.s_score
>=60 then 1 else 0 end)/SUM(case when a
.s_score
then 1 else 0 end)),2) as 及格率
,
ROUND(100*(SUM(case when a
.s_score
>=70 and a
.s_score
<=80 then 1 else 0 end)/SUM(case when a
.s_score
then 1 else 0 end)),2) as 中等率
,
ROUND(100*(SUM(case when a
.s_score
>=80 and a
.s_score
<=90 then 1 else 0 end)/SUM(case when a
.s_score
then 1 else 0 end)),2) as 优良率
,
ROUND(100*(SUM(case when a
.s_score
>=90 then 1 else 0 end)/SUM(case when a
.s_score
then 1 else 0 end)),2) as 优秀率
from score a
left join course b
on a
.c_id
= b
.c_id
GROUP BY a
.c_id
,b
.c_name
19、按各科成绩进行排序，并显示排名(实现不完全)
select a
.s_id
,a
.c_id
,
@i:
=@i +1 as i保留排名
,
@k:
=(case when @score=a
.s_score
then @k else @i end) as rank不保留排名
,
@score:
=a
.s_score
as score
from (
select s_id
,c_id
,s_score
from score
WHERE c_id
='01' GROUP BY s_id
,c_id
,s_score
ORDER BY s_score
DESC
)a
,(select @k:
=0,@i:
=0,@score:
=0)s
union
select a
.s_id
,a
.c_id
,
@i:
=@i +1 as i
,
@k:
=(case when @score=a
.s_score
then @k else @i end) as rank
,
@score:
=a
.s_score
as score
from (
select s_id
,c_id
,s_score
from score
WHERE c_id
='02' GROUP BY s_id
,c_id
,s_score
ORDER BY s_score
DESC
)a
,(select @k:
=0,@i:
=0,@score:
=0)s
union
select a
.s_id
,a
.c_id
,
@i:
=@i +1 as i
,
@k:
=(case when @score=a
.s_score
then @k else @i end) as rank
,
@score:
=a
.s_score
as score
from (
select s_id
,c_id
,s_score
from score
WHERE c_id
='03' GROUP BY s_id
,c_id
,s_score
ORDER BY s_score
DESC
)a
,(select @k:
=0,@i:
=0,@score:
=0)s
20、查询学生的总成绩并进行排名
select a
.s_id
,
@i:
=@i+1 as i
,
@k:
=(case when @score=a
.sum_score
then @k else @i end) as rank
,
@score:
=a
.sum_score
as score
from (select s_id
,SUM(s_score
) as sum_score
from score
GROUP BY s_id
ORDER BY sum_score
DESC)a
,
(select @k:
=0,@i:
=0,@score:
=0)s
21、查询不同老师所教不同课程平均分从高到低显示
select a
.t_id
,c
.t_name
,a
.c_id
,ROUND(avg(s_score
),2) as avg_score
from course a
left join score b
on a
.c_id
=b
.c_id
left join teacher c
on a
.t_id
=c
.t_id
GROUP BY a
.c_id
,a
.t_id
,c
.t_name
ORDER BY avg_score
DESC;
22、查询所有课程的成绩第2名到第3名的学生信息及该课程成绩
elect d
.*,c
.排名
,c
.s_score
,c
.c_id
from (
select a
.s_id
,a
.s_score
,a
.c_id
,@i:
=@i+1 as 排名
from score a
,(select @i:
=0)s
where a
.c_id
='01'
)c
left join student d
on c
.s_id
=d
.s_id
where 排名
BETWEEN 2 AND 3
UNION
select d
.*,c
.排名
,c
.s_score
,c
.c_id
from (
select a
.s_id
,a
.s_score
,a
.c_id
,@j:
=@j+1 as 排名
from score a
,(select @j:
=0)s
where a
.c_id
='02'
)c
left join student d
on c
.s_id
=d
.s_id
where 排名
BETWEEN 2 AND 3
UNION
select d
.*,c
.排名
,c
.s_score
,c
.c_id
from (
select a
.s_id
,a
.s_score
,a
.c_id
,@k:
=@k+1 as 排名
from score a
,(select @k:
=0)s
where a
.c_id
='03'
)c
left join student d
on c
.s_id
=d
.s_id
where 排名
BETWEEN 2 AND 3;
23、统计各科成绩各分数段人数：课程编号,课程名称,[100-85],[85-70],[70-60],[0-60]及所占百分比
select distinct f
.c_name
,a
.c_id
,b
.`85-100`,b
.百分比
,c
.`70-85`,c
.百分比
,d
.`60-70`,d
.百分比
,e
.`0-60`,e
.百分比
from score a
left join (select c_id
,SUM(case when s_score
>85 and s_score
<=100 then 1 else 0 end) as `85-100`,
ROUND(100*(SUM(case when s_score
>85 and s_score
<=100 then 1 else 0 end)/count(*)),2) as 百分比
from score
GROUP BY c_id
)b
on a
.c_id
=b
.c_id
left join (select c_id
,SUM(case when s_score
>70 and s_score
<=85 then 1 else 0 end) as `70-85`,
ROUND(100*(SUM(case when s_score
>70 and s_score
<=85 then 1 else 0 end)/count(*)),2) as 百分比
from score
GROUP BY c_id
)c
on a
.c_id
=c
.c_id
left join (select c_id
,SUM(case when s_score
>60 and s_score
<=70 then 1 else 0 end) as `60-70`,
ROUND(100*(SUM(case when s_score
>60 and s_score
<=70 then 1 else 0 end)/count(*)),2) as 百分比
from score
GROUP BY c_id
)d
on a
.c_id
=d
.c_id
left join (select c_id
,SUM(case when s_score
>=0 and s_score
<=60 then 1 else 0 end) as `0-60`,
ROUND(100*(SUM(case when s_score
>=0 and s_score
<=60 then 1 else 0 end)/count(*)),2) as 百分比
from score
GROUP BY c_id
)e
on a
.c_id
=e
.c_id
left join course f
on a
.c_id
= f
.c_id
– 24、查询学生平均成绩及其名次
select a
.s_id
,
@i:
=@i+1 as '不保留空缺排名',
@k:
=(case when @avg_score=a
.avg_s
then @k else @i end) as '保留空缺排名',
@avg_score:
=avg_s
as '平均分'
from (select s_id
,ROUND(AVG(s_score
),2) as avg_s
from score
GROUP BY s_id
)a
,(select @avg_score:
=0,@i:
=0,@k:
=0)b
;
25、查询各科成绩前三名的记录
select a
.s_id
,a
.c_id
,a
.s_score
from score a
left join score b
on a
.c_id
= b
.c_id
and a
.s_score
<b
.s_score
group by a
.s_id
,a
.c_id
,a
.s_score
HAVING COUNT(b
.s_id
)<3
ORDER BY a
.c_id
,a
.s_score
DESC
26、查询每门课程被选修的学生数
select c_id
,count(s_id
) from score a
GROUP BY c_id
27、查询出只有两门课程的全部学生的学号和姓名
select s_id
,s_name
from student
where s_id
in(
select s_id
from score
GROUP BY s_id
HAVING COUNT(c_id
)=2);
28、查询男生、女生人数
select s_sex
,COUNT(s_sex
) as 人数
from student
GROUP BY s_sex
29、查询名字中含有"风"字的学生信息
select * from student
where s_name
like '%风%';
30、查询同名同性学生名单，并统计同名人数
select a
.s_name
,a
.s_sex
,count(*) from student a
JOIN
student b
on a
.s_id
!=b
.s_id
and a
.s_name
= b
.s_name
and a
.s_sex
= b
.s_sex
GROUP BY a
.s_name
,a
.s_sex
31、查询1990年出生的学生名单
select s_name
from student
where s_birth
like '1990%'
32、查询每门课程的平均成绩，结果按平均成绩降序排列，平均成绩相同时，按课程编号升序排列
select c_id
,ROUND(AVG(s_score
),2) as avg_score
from score
GROUP BY c_id
ORDER BY avg_score
DESC,c_id
ASC
33、查询平均成绩大于等于85的所有学生的学号、姓名和平均成绩
select a
.s_id
,b
.s_name
,ROUND(avg(a
.s_score
),2) as avg_score
from score a
left join student b
on a
.s_id
=b
.s_id
GROUP BY s_id
HAVING avg_score
>=85
34、查询课程名称为"数学"，且分数低于60的学生姓名和分数
select a
.s_name
,b
.s_score
from score b
LEFT JOIN student a
on a
.s_id
=b
.s_id
where b
.c_id
=(
select c_id
from course
where c_name
='数学') and b
.s_score
<60
35、查询所有学生的课程及分数情况
select a
.s_id
,a
.s_name
,
SUM(case c
.c_name
when '语文' then b
.s_score
else 0 end) as '语文',
SUM(case c
.c_name
when '数学' then b
.s_score
else 0 end) as '数学',
SUM(case c
.c_name
when '英语' then b
.s_score
else 0 end) as '英语',
SUM(b
.s_score
) as '总分'
from student a
left join score b
on a
.s_id
= b
.s_id
left join course c
on b
.c_id
= c
.c_id
GROUP BY a
.s_id
,a
.s_name
36、查询任何一门课程成绩在70分以上的姓名、课程名称和分数；
select a
.s_name
,b
.c_name
,c
.s_score
from course b
left join score c
on b
.c_id
= c
.c_id
left join student a
on a
.s_id
=c
.s_id
where c
.s_score
>=70
37、查询不及格的课程
select a
.s_id
,a
.c_id
,b
.c_name
,a
.s_score
from score a
left join course b
on a
.c_id
= b
.c_id
where a
.s_score
<60
38、查询课程编号为01且课程成绩在80分以上的学生的学号和姓名；
select a
.s_id
,b
.s_name
from score a
LEFT JOIN student b
on a
.s_id
= b
.s_id
where a
.c_id
= '01' and a
.s_score
>80
39、求每门课程的学生人数
select count(*) from score
GROUP BY c_id
;
40、查询选修"张三"老师所授课程的学生中，成绩最高的学生信息及其成绩
select c_id
from course c
,teacher d
where c
.t_id
=d
.t_id
and d
.t_name
='张三'
select MAX(s_score
) from score
where c_id
='02'
select a
.*,b
.s_score
,b
.c_id
,c
.c_name
from student a
LEFT JOIN score b
on a
.s_id
= b
.s_id
LEFT JOIN course c
on b
.c_id
=c
.c_id
where b
.c_id
=(select c_id
from course c
,teacher d
where c
.t_id
=d
.t_id
and d
.t_name
='张三')
and b
.s_score
in (select MAX(s_score
) from score
where c_id
='02')
41、查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩
select DISTINCT b
.s_id
,b
.c_id
,b
.s_score
from score a
,score b
where a
.c_id
!= b
.c_id
and a
.s_score
= b
.s_score
42、查询每门功成绩最好的前两名
select a
.s_id
,a
.c_id
,a
.s_score
from score a
where (select COUNT(1) from score b
where b
.c_id
=a
.c_id
and b
.s_score
>=a
.s_score
)<=2 ORDER BY a
.c_id
43、统计每门课程的学生选修人数（超过5人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，若人数相同，按课程号升序排列
select c_id
,count(*) as total
from score
GROUP BY c_id
HAVING total
>5 ORDER BY total
,c_id
ASC
44、检索至少选修两门课程的学生学号
select s_id
,count(*) as sel
from score
GROUP BY s_id
HAVING sel
>=2
45、查询选修了全部课程的学生信息
select * from student
where s_id
in(
select s_id
from score
GROUP BY s_id
HAVING count(*)=(select count(*) from course
))
46、查询各学生的年龄
select s_birth
,(DATE_FORMAT
(NOW(),'%Y')-DATE_FORMAT
(s_birth
,'%Y') -
(case when DATE_FORMAT
(NOW(),'%m%d')>DATE_FORMAT
(s_birth
,'%m%d') then 0 else 1 end)) as age
from student
;
47、查询本周过生日的学生
select * from student
where WEEK
(DATE_FORMAT
(NOW(),'%Y%m%d'))=WEEK
(s_birth
)
select * from student
where YEARWEEK
(s_birth
)=YEARWEEK
(DATE_FORMAT
(NOW(),'%Y%m%d'))
select WEEK
(DATE_FORMAT
(NOW(),'%Y%m%d'))
48、查询下周过生日的学生
select * from student
where WEEK
(DATE_FORMAT
(NOW(),'%Y%m%d'))+1 =WEEK
(s_birth
)
49、查询本月过生日的学生
select * from student
where MONTH(DATE_FORMAT
(NOW(),'%Y%m%d')) =MONTH(s_birth
)
50、查询下月过生日的学生
select * from student
where MONTH(DATE_FORMAT
(NOW(),'%Y%m%d'))+1 =MONTH(s_birth
)
