sql练习50题

于 2021-11-21 20:31:56 发布
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本文链接：https://blog.youkuaiyun.com/weixin_58751888/article/details/121459590
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```
--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);
```

-- 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 * from (SELECT s_id,s_score from score where c_id = 01) as t1,
(SELECT s_id,s_score from score where c_id = 02) as t2 where t1.s_id = t2.s_id and t1.s_score >t2.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 * from 
(SELECT s_id,s_score from score where c_id = 01) as t1,
(SELECT s_id,s_score from score where c_id = 02) as t2	where t1.s_id = t2.s_id and t1.s_score < t2.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 stu.s_name, t1.s_id,t1.avg FROM (SELECT s_id,avg(s_score) as avg FROM score GROUP BY s_id HAVING avg(s_score)>=60) as t1 ,student as stu where stu.s_id = t1.s_id

-- 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)
SELECT stu.s_name,t1.s_id,t1.avg from 
(SELECT s_id,AVG(s_score) as avg from score GROUP BY s_id HAVING avg < 60) as t1 ,student as stu	where stu.s_id = t1.s_id

-- 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 stu.s_name,t1.s_id,t1.count,t1.sum from student as stu,
(SELECT s_id,count(c_id) as count,SUM(s_score) as sum FROM score GROUP BY s_id) as t1 where t1.s_id = stu.s_id
​			
-- 6、查询"李"姓老师的数量 
SELECT COUNT(t_name) as '数量' 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 s_name,s_sex,s_birth from student where s_id 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 like '张三')))

-- 8、查询没学过"张三"老师授课的同学的信息 
SELECT s_name,s_birth,s_sex from student where 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')))

-- 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 dd.id,stu.s_name,stu.s_birth,stu.s_sex from 
(SELECT t1.s_id as id from 
(SELECT s_id from score where c_id = 01) as t1,
(SELECT s_id from score where c_id = 02) as t2 where t1.s_id = t2.s_id) as dd ,student as stu
where dd.id = stu.s_id
​	
-- 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 t1.s_id,stu.s_name,stu.s_birth,stu.s_sex FROM
(SELECT s_id FROM score where c_id = 01) as t1,
(SELECT s_id FROM score where s_id not in (SELECT s_id FROM score where c_id = 02) GROUP BY s_id) as t2,student as stu where t1.s_id = t2.s_id and stu.s_id = t1.s_id
​			

-- 11、查询没有学全所有课程的同学的信息 
SELECT s_id,s_name,s_sex,s_birth from student where s_id not in (SELECT t1.s_id from 
(SELECT s_id from score where c_id = 01) as t1,
(SELECT s_id from score where c_id = 02) as t2,
(SELECT s_id from score where c_id = 03) as t3 where t1.s_id = t2.s_id and t2.s_id = t3.s_id)

-- 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 s_id from score where c_id in (01,02,03) GROUP BY s_id)

-- 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 * from student where s_id in(
SELECT s_id from score where c_id in (01,02,03)  GROUP BY s_id HAVING COUNT(s_id) = 3)

-- 14、查询没学过"张三"老师讲授的任一门课程的学生姓名 
SELECT s_name from student where s_id not in ( 
SELECT s_id from score where c_id  in (
SELECT c_id from course where t_id in ( 
SELECT t_id from teacher where t_name = '张三')))

-- 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 stu.s_id,stu.s_name, t1.avg from 
(SELECT s_id,avg(s_score) as avg from score where s_score < 60 GROUP BY s_id HAVING COUNT(s_id) >= 2) as t1 , student as stu where t1.s_id = stu.s_id

-- 16、检索"01"课程分数小于60，按分数降序排列的学生信息
SELECT * from student where s_id in (
SELECT s_id FROM score where s_score < 60 and c_id = 01 ORDER BY 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 * from 
(SELECT s.s_id,stu.s_name,AVG(s.s_score) as avg from student as stu,score as s,course as c where s.c_id = c.c_id and stu.s_id= s.s_id GROUP BY s.s_id ORDER BY avg DESC) as t1 LEFT JOIN (SELECT s.s_id,s.s_score,c.c_name from course as c,score as s where s.c_id=c.c_id) as s on s.s_id = t1.s_id

-- 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
SELECT c_id,max(s_score) as 最高分,MIN(s_score) as 最低分,AVG(s_score) as 平均分,COUNT(*) as 选修人数,SUM(case when s_score >=60 then 1 else 0 end )/count(*) as 及格率,SUM(case when  s_score >=70 and s_score< 80 then 1 else 0 end)/COUNT(*) as 中等率,SUM(case when 80 <= s_score and s_score < 90 then 1 else 0 end)/COUNT(*) as 优良率, SUM(case when s_score >=90 then 1 else 0 end)/COUNT(*) as 优秀率 from score  GROUP BY c_id
​	
-- 19、按各科成绩进行排序，并显示排名



-- 20、查询学生的总成绩并进行排名
SELECT stu.s_name,sum(s.s_score) as sum1 from student as stu ,score as s where s.s_id = stu.s_id GROUP BY s.s_id ORDER BY sum1 DESC

-- 21、查询不同老师所教不同课程平均分从高到低显示 
SELECT s.c_id,n.name,avg(s.s_score) as avg from score as s ,(SELECT c.c_id,t.t_name as name from course as c,teacher as t where c.t_id = t.t_id) as n where n.c_id = s.c_id GROUP BY c_id ORDER BY avg 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
(SELECT s.s_id,c.c_id,s.s_score,stu.s_name,stu.s_birth,c.c_name from score as s,course as c,student as stu where s.c_id = 01 and s.s_id = stu.s_id and s.c_id = c.c_id ORDER BY s.s_score DESC LIMIT 1,2)
UNION all 
(SELECT s.s_id,c.c_id,s.s_score,stu.s_name,stu.s_birth,c.c_name from score as s,course as c,student as stu where s.c_id = 02 and s.s_id = stu.s_id and s.c_id = c.c_id ORDER BY s.s_score DESC LIMIT 1,2 )
union all
(SELECT s.s_id,c.c_id,s.s_score,stu.s_name,stu.s_birth,c.c_name from score as s,course as c,student as stu where s.c_id = 03 and s.s_id = stu.s_id and s.c_id = c.c_id ORDER BY s.s_score DESC LIMIT 1,2)
​			
-- 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 s.c_id,c.c_name,sum(case when s.s_score >85 and s.s_score <100 then 1 else 0 end)/count(s.s_score) as '[100-85]所占百分比',sum(case when s.s_score <= 85 and s.s_score > 70 then 1 else 0 end)/count(s.s_score) as '[85-70]所占百分比',sum(case when s.s_score >60 and s.s_score <= 70 then 1 else 0 end)/count(s.s_score) as '[70-60]所占百分比',sum(case when s.s_score >0 and s.s_score <= 60 then 1 else 0 end)/count(s.s_score) as '[0-60]所占百分比' from score as s ,course as c where s.c_id = c.c_id and s.c_id = 01
UNION all
SELECT s.c_id,c.c_name,sum(case when s.s_score >85 and s.s_score <100 then 1 else 0 end)/count(s.s_score) as '[100-85]所占百分比',sum(case when s.s_score <= 85 and s.s_score > 70 then 1 else 0 end)/count(s.s_score) as '[85-70]所占百分比',sum(case when s.s_score >60 and s.s_score <= 70 then 1 else 0 end)/count(s.s_score) as '[70-60]所占百分比',sum(case when s.s_score >0 and s.s_score <= 60 then 1 else 0 end)/count(s.s_score) as '[0-60]所占百分比' from score as s ,course as c where s.c_id = c.c_id and s.c_id = 02
UNION all
SELECT s.c_id,c.c_name,sum(case when s.s_score >85 and s.s_score <100 then 1 else 0 end)/count(s.s_score) as '[100-85]所占百分比',sum(case when s.s_score <= 85 and s.s_score > 70 then 1 else 0 end)/count(s.s_score) as '[85-70]所占百分比',sum(case when s.s_score >60 and s.s_score <= 70 then 1 else 0 end)/count(s.s_score) as '[70-60]所占百分比',sum(case when s.s_score >0 and s.s_score <= 60 then 1 else 0 end)/count(s.s_score) as '[0-60]所占百分比' from score as s ,course as c where s.c_id = c.c_id and s.c_id = 03
​				 
-- 24、查询学生平均成绩及其名次 
SELECT stu.s_name,avg(s.s_score) as avg from student as stu,score as s where stu.s_id = s.s_id GROUP BY s.s_id ORDER BY avg DESC

-- 25、查询各科成绩前三名的记录
(SELECT c.c_name,stu.s_name,s.s_id,s.c_id,s.s_score from student as stu , score as s ,course as c where stu.s_id = s.s_id and s.c_id = c.c_id and s.c_id = 01 ORDER BY s.s_score DESC LIMIT 3	)		
UNION all
(SELECT c.c_name,stu.s_name,s.s_id,s.c_id,s.s_score from student as stu , score as s ,course as c where stu.s_id = s.s_id and s.c_id = c.c_id and s.c_id = 02 ORDER BY s.s_score DESC LIMIT 3)
UNION all
(SELECT c.c_name,stu.s_name,s.s_id,s.c_id,s.s_score from student as stu , score as s ,course as c where stu.s_id = s.s_id and s.c_id = c.c_id and s.c_id = 03 ORDER BY s.s_score DESC LIMIT 3)

-- 26、查询每门课程被选修的学生数 
SELECT c.c_name,count(s.s_id) from course as c ,score as s where c.c_id = s.c_id GROUP BY c.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.s_id,stu.s_name,count(s.c_id) as num from score as s ,student as stu where s.c_id in (01,02,03) and s.s_id = stu.s_id GROUP BY s.s_id HAVING num = 2
​		
​		
-- 28、查询男生、女生人数 
SELECT s_sex,count(s_sex) 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 s_id, s_name,s_sex,count(*) from student where s_id != s_id and s_name = s_name and s_sex = s_sex GROUP BY s_id



-- 31、查询1990年出生的学生名单
SELECT * 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,avg(s_score) as avg from score GROUP BY c_id ORDER BY avg 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 s.s_id,stu.s_name,avg(s.s_score) as avg from score as s ,student as stu where s.s_id = stu.s_id GROUP BY s.s_id HAVING avg > 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 stu.s_name,s.s_score from course as c, student as stu ,score as s where c.c_id = s.c_id and s.s_id = stu.s_id and c.c_name = "数学" HAVING s.s_score < 60

-- 35、查询所有学生的课程及分数情况； 
SELECT stu.s_name,c.c_name,s.s_score from course as c, student as stu ,score as s where c.c_id = s.c_id and s.s_id = stu.s_id

 -- 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 stu.s_name,c.c_name,s.s_score from course as c, student as stu ,score as s where c.c_id = s.c_id and s.s_id = stu.s_id and s.s_score > 70 

-- 37、查询不及格的课程
​	SELECT stu.s_name,c.c_name,s.s_score from course as c, student as stu ,score as s where c.c_id = s.c_id and s.s_id = stu.s_id and s.s_score < 70	
​		
--38、查询课程编号为02且课程成绩在80分以上的学生的学号和姓名；
SELECT s_id ,s_name from student where s_id in ( 
SELECT s_id from score where s_score > 80 and c_id = 02)

-- 39、求每门课程的学生人数 
SELECT c_id,count(s_id) as "学生人数" 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 stu.*,t1.max from (SELECT s_id,max(s_score) as max from score where c_id in (
SELECT c_id from course where t_id in(
SELECT t_id from teacher where t_name = "张三"))) as t1,student as stu where stu.s_id = t1.s_id

-- 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 s_id,s_name,s_birth from student where s_id in (
SELECT t1.s_id from (SELECT s_id,c_id,s_score from score where c_id = 01) as t1,
(SELECT s_id,c_id,s_score from score where c_id = 02) as t2,
(SELECT s_id,c_id,s_score from score where c_id = 03) as t3 where t1.s_id = t2.s_id and t2.s_id = t3.s_id and t1.s_score=t2.s_score and t2.s_score=t3.s_score)
​	

-- 42、查询每门功成绩最好的前两名  
(SELECT * from score where c_id = 01 ORDER BY s_score DESC LIMIT 1,2)
UNION all
(SELECT * from score where c_id = 02 ORDER BY s_score DESC LIMIT 1,2)
UNION ALL
(SELECT * from score where c_id = 03 ORDER BY s_score DESC LIMIT 1,2)
-- 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(c_id) as num from score GROUP BY c_id ORDER BY num DESC,c_id ASC		
​		
​		
-- 44、检索至少选修两门课程的学生学号 
SELECT s_id, COUNT(c_id) as cnum from score GROUP BY s_id HAVING cnum >= 2

-- 45、查询选修了全部课程的学生信息 
SELECT s_id, COUNT(c_id) as cnum from score where c_id in (01,02,03) GROUP BY s_id HAVING cnum = 3



--46、查询各学生的年龄
SELECT s_id,year(NOW())-year(s_birth) from student



-- 47、查询本周过生日的学生
​	select *
from student 
where YEARWEEK(s_birth)=YEARWEEK(now())
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