MySQL经典练习题及答案,常用SQL语句练习50题

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所属分类:数据管理
  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

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);

题目

  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"01"课程比"02"课程成绩低的学生的信息及课程分数
  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
  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(包括有成绩的和无成绩的)
  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
  6. 查询"李"姓老师的数量
  7. 查询学过"张三"老师授课的同学的信息
  8. 查询没学过"张三"老师授课的同学的信息
  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
  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
  11. 查询没有学全所有课程的同学的信息
  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
  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
  14. 查询没学过"张三"老师讲授的任一门课程的学生姓名
  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
  16. 检索"01"课程分数小于60,按分数降序排列的学生信息
  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
  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,优秀率及格为>=60,中等为:70-80,优良为:80-90,优秀为:>=90
  19. 按各科成绩进行排序,并显示排名(实现不完全)mysql没有rank函数
  20. 查询学生的总成绩并进行排名
  21. 查询不同老师所教不同课程平均分从高到低显示
  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
  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
  24. 查询学生平均成绩及其名次
  25. 查询各科成绩前三名的记录
    1选出b表比a表成绩大的所有组
    2.选出比当前id成绩大的 小于三个的
  26. 查询每门课程被选修的学生数
  27. 查询出只有两门课程的全部学生的学号和姓名
  28. 查询男生、女生人数
  29. 查询名字中含有"风"字的学生信息
  30. 查询同名同性学生名单,并统计同名人数
  31. 查询1990年出生的学生名单
  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
  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
  34. 查询课程名称为"数学",且分数低于60的学生姓名和分数\
  35. 查询所有学生的课程及分数情况;
  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;
  37. 查询不及格的课程
  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;
  39. 求每门课程的学生人数
  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
  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
  42. 查询每门功成绩最好的前两名
  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
  44. 检索至少选修两门课程的学生学号
  45. 查询选修了全部课程的学生信息
  46. 查询各学生的年龄 按照出生日期来算,当前月日 < 出生年月的月日则,年龄减一
  47. 查询本周过生日的学生
  48. 查询下周过生日的学生
  49. 查询本月过生日的学生
  50. 查询下月过生日的学生

参考答案

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

-- 7题
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题
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题
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题
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题
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题
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题
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题
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题
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题
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题
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题
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题
-- mysql没有rank函数
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题
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题
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题
select 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题

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题
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题
-- 1.选出b表比a表成绩大的所有组
-- 2.选出比当前id成绩大的 小于三个的
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题

select c_id,count(s_id) from score a GROUP BY c_id

-- 27题
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题
select s_sex,COUNT(s_sex) as 人数  from student GROUP BY s_sex

-- 29题

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

-- 30题

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题

select s_name from student where s_birth like '1990%'

-- 32题

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题 

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题

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题


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题 
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题
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题
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题
select count(*) from score GROUP BY c_id;

-- 40题


-- 查询老师id   
select c_id from course c,teacher d where c.t_id=d.t_id and d.t_name='张三'
-- 查询最高分(可能有相同分数)
select MAX(s_score) from score where c_id='02'
-- 查询信息
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题
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题
-- 牛逼的写法
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题
select c_id,count(*) as total from score GROUP BY c_id HAVING total>5 ORDER BY total,c_id ASC
-- 44题
select s_id,count(*) as sel from score GROUP BY s_id HAVING sel>=2
-- 45题
select * from student where s_id in(        
select s_id from score GROUP BY s_id HAVING count(*)=(select count(*) from course))
--46题
-- 按照出生日期来算,当前月日 < 出生年月的月日则,年龄减一
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题
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题
select * from student where WEEK(DATE_FORMAT(NOW(),'%Y%m%d'))+1 =WEEK(s_birth)

-- 49题

select * from student where MONTH(DATE_FORMAT(NOW(),'%Y%m%d')) =MONTH(s_birth)

-- 50题
select * from student where MONTH(DATE_FORMAT(NOW(),'%Y%m%d'))+1 =MONTH(s_birth)
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