MySQL经典练习题及答案，常用SQL语句练习50题

MySQL经典练习题及答案，常用SQL语句练习50题，题目来源
https://www.cnblogs.com/Diyo/p/11424844.html

环境准备

建表语句

-- 1.学生表 
CREATE TABLE `Student` (
    `s_id` VARCHAR(20),             -- 学生编号，主键
    s_name VARCHAR(20) NOT NULL DEFAULT '',    -- 学生姓名，不能为空，默认为空字符串
    s_brith VARCHAR(20) NOT NULL DEFAULT '',   -- 出生年月，不能为空，默认为空字符串
    s_sex VARCHAR(10) NOT NULL DEFAULT '',     -- 学生性别，不能为空，默认为空字符串
    PRIMARY KEY(s_id)               -- 设置s_id为主键
);

-- 2.课程表 
CREATE TABLE Course(
    c_id varchar(20),               -- 课程编号，主键
    c_name VARCHAR(20) NOT NULL DEFAULT '',    -- 课程名称，不能为空，默认为空字符串
    t_id VARCHAR(20) NOT NULL,      -- 教师编号，不能为空
    PRIMARY KEY(c_id)               -- 设置c_id为主键
);


-- 3.教师表 
CREATE TABLE Teacher(
    t_id VARCHAR(20),               -- 教师编号，主键
    t_name VARCHAR(20) NOT NULL DEFAULT '',    -- 教师姓名，不能为空，默认为空字符串
    PRIMARY KEY(t_id)               -- 设置t_id为主键
);


-- 4.成绩表 
CREATE TABLE Score
    s_id VARCHAR(20),               -- 学生编号，联合主键的一部分
    c_id VARCHAR(20) NOT NULL DEFAULT '',      -- 课程编号，联合主键的一部分，不能为空，默认为空字符串
    s_score INT(3),                 -- 分数，整数类型，最大3位数
    PRIMARY KEY(`s_id`,`c_id`)      -- 设置(s_id, c_id)为联合主键
);

插入数据


--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);

数据预览

学生表

s_id	s_name	s_bin	s_sex
01	赵雷	1990-01-01	男
02	钱电	1990-12-21	男
03	孙风	1990-05-20	男
04	李云	1990-08-06	男
05	周梅	1991-12-01	女
06	吴兰	1992-03-01	女
07	郑竹	1989-07-01	女
08	王菊	1990-01-20	女

课程表

c_id	c_name	t_id
01	语文	02
02	数学	01
03	英语	03

教师表

t_id	t_name
01	张三
02	李四
03	王五

成绩表

s_id	c_id	s_score
01	01	80
01	02	90
01	03	99
02	01	70
02	02	60
02	03	80
03	01	80
03	02	80
03	03	80
04	01	50
04	02	30
04	03	20
05	01	76
05	02	87
06	01	31
06	03	34
07	02	89
07	03	98

题目解析

查询”01”课程比”02”课程成绩高的学生的信息及课程分数

select s.*,
       a.s_score as score_01,
       b.s_score as score_02
from score a,
     score b,
     student s
where a.s_id = b.s_id
  and a.c_id = '01'
  and b.c_id = '02'
  and a.s_score > b.s_score
  and s.s_id = a.s_id;

查询”01”课程比”02”课程成绩低的学生的信息及课程分数

select s.*,
       a.s_score as score_01,
       b.s_score as score_02
from score a,
     score b,
     student s
where a.s_id = b.s_id
  and a.c_id = '01'
  and b.c_id = '02'
  and a.s_score < b.s_score
  and s.s_id = a.s_id;

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 stu.*, avg(s_score) as avg_score
from score sc,
     student stu
where sc.s_id = stu.s_id
group by s_id
having avg(s_score) >= 60;

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 stu.*, IFNULL(avg(s_score), 0) as avg_score
from student stu
    left join score sc
    on sc.s_id = stu.s_id
group by s_id
having IFNULL(avg(s_score), 0) < 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 stu.*, count(sc.c_id) as course_sum, 
    ifnull(sum(sc.s_score), 0) as score_sum
from student stu
    left join score sc
    on stu.s_id = sc.s_id
group by stu.s_id;

查询”李”姓老师的数量

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2
3

select count(1)
from teacher
where t_name like '李%';

查询学过”张三”老师授课的同学的信息

select stu.*,c.c_name,t.t_name
from student stu,
    course c,
     score sc,
     teacher t
where c.c_id = sc.c_id
  and t.t_id = c.t_id
  and sc.s_id = stu.s_id
  and t.t_name = '张三';

查询没学过”张三”老师授课的同学的信息
这个题目有个小技巧，就是用not in

select *
from student
where s_id not in 
  (select stu.s_id
   from student stu,
        course c,
        score sc,
        teacher t
   where c.c_id = sc.c_id
     and t.t_id = c.t_id
     and sc.s_id = stu.s_id
     and t.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 stu.*
from score a,
     score b,
     student stu
where a.c_id = '01'
  and b.c_id = '02'
  and a.s_id = b.s_id
  and stu.s_id = a.s_id;

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

# 长型变整型
select stu.* 
from (select sc.s_id,
             max(case when sc.c_id = '01' then s_score end) as score_01,
             max(case when sc.c_id = '02' then s_score end) as score_02,
             max(case when sc.c_id = '03' then s_score end) as score_03
      from score sc
      group by s_id) t,
     student stu
where t.score_01 is not null
  and t.score_02 is null
  and t.s_id = stu.s_id;

查询没有学全所有课程的同学的信息

select stu.*
from student stu
         left join score sc
                   on stu.s_id = sc.s_id
group by stu.s_id
having count(sc.c_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 distinct stu.*
from student stu
         left join score sc
                   on stu.s_id = sc.s_id
where sc.c_id in (select c_id from score where s_id = '01');

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 *
from student
where s_id not in 
    (select s_id
    from (select t.*, sc.c_id cid2
         from (select *
               from student
                  , (select c_id from score where s_id = '01') t) t
                  left join score sc
                            on t.s_id = sc.s_id
                                and t.c_id = sc.c_id
         union
         select t.*, sc.c_id cid2
         from (select *
               from student
                  , (select c_id from score where s_id = '01') t) t
                  right join score sc
                             on t.s_id = sc.s_id
                                 and t.c_id = sc.c_id) tt
    where cid2 is null
    group by s_id)
and s_id != '01';

查询没学过”张三”老师讲授的任一门课程的学生姓名

select stu.*
from student stu
where s_id not in 
  (select s_id
   from score
   where score.c_id in 
      (select c_id
      from course
      where t_id = (select t_id from teacher where t_name = '张三'))
      group by s_id);

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 stu.s_id, stu.s_name, ifnull(avg(score.s_score), 0)
from student stu
    left join score
       on stu.s_id = score.s_id
group by stu.s_id
having sum(case when score.s_score >= 60 then 0 else 1 end) >= 2

检索”01”课程分数小于60，按分数降序排列的学生信息

select stu.*, sc.s_score
from student stu
join score sc on stu.s_id = sc.s_id
where sc.c_id = '01' and sc.s_score < 60
order by sc.s_score desc;

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 s.s_id, s.s_name, sc.c_id, sc.s_score,
       round(avg(sc.s_score) over (partition by s.s_id),2) as avg_score
from student s
join score sc on s.s_id = sc.s_id
order by avg_score desc, s.s_id;

查询各科成绩最高分、最低分和平均分（及格率、中等率、优良率、优秀率）

select c.c_id, c.c_name,
       max(sc.s_score) as max_score,
       min(sc.s_score) as min_score,
       round(avg(sc.s_score),2) as avg_score,
       concat(round(sum(case when sc.s_score >= 60 then 1 else 0 end)/count(*)*100,2),'%') as pass_rate,
       concat(round(sum(case when sc.s_score between 60 and 69 then 1 else 0 end)/count(*)*100,2),'%') as medium_rate,
       concat(round(sum(case when sc.s_score between 70 and 84 then 1 else 0 end)/count(*)*100,2),'%') as good_rate,
       concat(round(sum(case when sc.s_score >= 85 then 1 else 0 end)/count(*)*100,2),'%') as excellent_rate
from course c
left join score sc on c.c_id = sc.c_id
group by c.c_id, c.c_name;

按各科成绩进行排序，并显示排名

select sc.c_id, c.c_name, sc.s_id, stu.s_name, sc.s_score,
       row_number() over (partition by sc.c_id order by sc.s_score desc) as rank
from score sc
join student stu on sc.s_id = stu.s_id
join course c on sc.c_id = c.c_id
order by sc.c_id, rank;

查询学生的总成绩并进行排名

select s.s_id, s.s_name, ifnull(sum(sc.s_score),0) as total_score,
       rank() over (order by ifnull(sum(sc.s_score),0) desc) as rank
from student s
left join score sc on s.s_id = sc.s_id
group by s.s_id, s.s_name
order by total_score desc;

查询不同老师所教不同课程平均分从高到低显示

select t.t_id, t.t_name, c.c_id, c.c_name, round(avg(sc.s_score),2) as avg_score
from teacher t
join course c on t.t_id = c.t_id
left join score sc on c.c_id = sc.c_id
group by t.t_id, t.t_name, c.c_id, c.c_name
order by avg_score desc;

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

with ranked as (
  select sc.c_id, c.c_name, sc.s_id, stu.s_name, sc.s_score,
         row_number() over (partition by sc.c_id order by sc.s_score desc) as rn
  from score sc
  join student stu on sc.s_id = stu.s_id
  join course c on sc.c_id = c.c_id
)
select * from ranked where rn between 2 and 3 order by c_id, rn;

统计各科成绩各分数段人数及所占百分比

select c.c_id, c.c_name,
       sum(case when sc.s_score between 85 and 100 then 1 else 0 end) as `100_85`,
       round(sum(case when sc.s_score between 85 and 100 then 1 else 0 end)/count(sc.s_id)*100,2) as `100_85_pct`,
       sum(case when sc.s_score between 70 and 84 then 1 else 0 end) as `85_70`,
       round(sum(case when sc.s_score between 70 and 84 then 1 else 0 end)/count(sc.s_id)*100,2) as `85_70_pct`,
       sum(case when sc.s_score between 60 and 69 then 1 else 0 end) as `70_60`,
       round(sum(case when sc.s_score between 60 and 69 then 1 else 0 end)/count(sc.s_id)*100,2) as `70_60_pct`,
       sum(case when sc.s_score < 60 then 1 else 0 end) as `0_60`,
       round(sum(case when sc.s_score < 60 then 1 else 0 end)/count(sc.s_id)*100,2) as `0_60_pct`
from course c
left join score sc on c.c_id = sc.c_id
group by c.c_id, c.c_name;

查询学生平均成绩及其名次

select s.s_id, s.s_name, round(ifnull(avg(sc.s_score),0),2) as avg_score,
       rank() over (order by round(ifnull(avg(sc.s_score),0),2) desc) as rank
from student s
left join score sc on s.s_id = sc.s_id
group by s.s_id, s.s_name
order by avg_score desc;

查询各科成绩前三名的记录

select *
from (
  select sc.c_id, c.c_name, sc.s_id, stu.s_name, sc.s_score,
         row_number() over (partition by sc.c_id order by sc.s_score desc) as rn
  from score sc
  join student stu on sc.s_id = stu.s_id
  join course c on sc.c_id = c.c_id
) t
where rn <= 3
order by c_id, rn;

查询每门课程被选修的学生数

select c.c_id, c.c_name, count(distinct sc.s_id) as student_count
from course c
left join score sc on c.c_id = sc.c_id
group by c.c_id, c.c_name;

查询出只有两门课程的全部学生的学号和姓名

select s.s_id, s.s_name
from student s
join score sc on s.s_id = sc.s_id
group by s.s_id, s.s_name
having count(distinct sc.c_id) = 2;

查询男生、女生人数

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3

select s_sex, count(*) as cnt
from student
group by s_sex;

查询名字中含有”风”字的学生信息

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2
3

select *
from student
where s_name like '%风%';

查询同名同性学生名单，并统计同名人数

select s_name, s_sex, count(*) as cnt, group_concat(s_id) as s_ids
from student
group by s_name, s_sex
having count(*) > 1;

查询1990年出生的学生名单

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2
3

select *
from student
where s_brith like '1990%';

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.c_id, c.c_name, round(avg(sc.s_score),2) as avg_score
from course c
left join score sc on c.c_id = sc.c_id
group by c.c_id, c.c_name
order by avg_score desc, c.c_id asc;

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 s.s_id, s.s_name, round(avg(sc.s_score),2) as avg_score
from student s
join score sc on s.s_id = sc.s_id
group by s.s_id, s.s_name
having avg(sc.s_score) >= 85;

查询课程名称为”数学”，且分数低于60的学生姓名和分数

select stu.s_id, stu.s_name, sc.s_score
from score sc
join course c on sc.c_id = c.c_id
join student stu on sc.s_id = stu.s_id
where c.c_name = '数学' and sc.s_score < 60;

查询所有学生的课程及分数情况

select s.s_id, s.s_name, c.c_id, c.c_name, sc.s_score
from student s
left join score sc on s.s_id = sc.s_id
left join course c on sc.c_id = c.c_id
order by s.s_id;

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 stu.s_name, c.c_name, sc.s_score
from score sc
join student stu on sc.s_id = stu.s_id
join course c on sc.c_id = c.c_id
where sc.s_score > 70;

查询不及格的课程记录

select c.c_id, c.c_name, sc.s_id, stu.s_name, sc.s_score
from score sc
join course c on sc.c_id = c.c_id
join student stu on sc.s_id = stu.s_id
where sc.s_score < 60;

求每门课程的学生人数

select c.c_id, c.c_name, count(sc.s_id) as student_count
from course c
left join score sc on c.c_id = sc.c_id
group by c.c_id, c.c_name;

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（按课程）

select c.c_id, c.c_name, sc.s_id, stu.s_name, sc.s_score
from score sc
join course c on sc.c_id = c.c_id
join teacher t on c.t_id = t.t_id
join student stu on sc.s_id = stu.s_id
where t.t_name = '张三'
  and sc.s_score = (select max(s_score) from score where c_id = c.c_id);

查询不同课程成绩相同的学生的学生编号、课程编号、学成绩

select a.s_id, a.c_id, a.s_score
from score a
join score b on a.s_id = b.s_id and a.s_score = b.s_score and a.c_id <> b.c_id
group by a.s_id, a.c_id, a.s_score;

查询每门课程成绩最好的前两名

select *
from (
  select sc.c_id, c.c_name, sc.s_id, stu.s_name, sc.s_score,
         row_number() over (partition by sc.c_id order by sc.s_score desc) as rn
  from score sc
  join student stu on sc.s_id = stu.s_id
  join course c on sc.c_id = c.c_id
) t
where rn <= 2
order by c_id, rn;

统计每门课程的学生选修人数（超过5人的课程才统计）

select c.c_id, count(distinct sc.s_id) as cnt
from course c
join score sc on c.c_id = sc.c_id
group by c.c_id
having count(distinct sc.s_id) > 5
order by cnt desc, c.c_id asc;

检索至少选修两门课程的学生学号

select s_id
from score
group by s_id
having count(distinct c_id) >= 2;

查询选修了全部课程的学生信息

select s.s_id, s.s_name
from student s
join score sc on s.s_id = sc.s_id
group by s.s_id, s.s_name
having count(distinct sc.c_id) = (select count(*) from course);

查询本周过生日的学生

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3

select *
from student
where weekofyear(str_to_date(s_brith, '%Y-%m-%d')) = weekofyear(curdate());

查询下周过生日的学生

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2
3

select *
from student
where weekofyear(str_to_date(s_brith, '%Y-%m-%d')) = weekofyear(curdate() + interval 1 week);

查询本月过生日的学生

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2
3

select *
from student
where month(str_to_date(s_brith, '%Y-%m-%d')) = month(curdate());

查询下月过生日的学生

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2
3

select *
from student
where month(str_to_date(s_brith, '%Y-%m-%d')) = month(curdate() + interval 1 month);

s_id	c_id	s_score
01	01	80
01	02	90
01	03	99
02	01	70
02	02	60
02	03	80
03	01	80
03	02	80
03	03	80
04	01	50
04	02	30
04	03	20
05	01	76
05	02	87
06	01	31
06	03	34
07	02	89
07	03	98

s_id	c_id	s_score
01	01	80
01	02	90
01	03	99
02	01	70
02	02	60
02	03	80
03	01	80
03	02	80
03	03	80
04	01	50
04	02	30
04	03	20
05	01	76
05	02	87
06	01	31
06	03	34
07	02	89
07	03	98

s_id	c_id	s_score
01	01	80
01	02	90
01	03	99
02	01	70
02	02	60
02	03	80
03	01	80
03	02	80
03	03	80
04	01	50
04	02	30
04	03	20
05	01	76
05	02	87
06	01	31
06	03	34
07	02	89
07	03	98