转载：50道sql题

最新推荐文章于 2024-06-08 17:41:43 发布

转载最新推荐文章于 2024-06-08 17:41:43 发布 · 218 阅读

--1.学生表
Student(S,Sname,Sage,Ssex) --S 学生编号,Sname 学生姓名,Sage 出生年月,Ssex 学生性别
--2.课程表
Course(C,Cname,T) --C --课程编号,Cname 课程名称,T 教师编号
--3.教师表
Teacher(T,Tname) --T 教师编号,Tname 教师姓名
--4.成绩表
SC(S,C,score) --S 学生编号,C 课程编号,score 分数
CREATE DATABASE students;
USE students;
CREATE TABLE Student(S VARCHAR(10),Sname VARCHAR(10),Sage DATETIME,Ssex VARCHAR(10));
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');
CREATE TABLE Course(C VARCHAR(10),Cname VARCHAR(10),T VARCHAR(10));
INSERT INTO Course VALUES('01' , '语文' , '02');
INSERT INTO Course VALUES('02' , '数学' , '01');
INSERT INTO Course VALUES('03' , '英语' , '03');
CREATE TABLE Teacher(T VARCHAR(10),Tname VARCHAR(10));
INSERT INTO Teacher VALUES('01' , '张三');
INSERT INTO Teacher VALUES('02' , '李四');
INSERT INTO Teacher VALUES('03' , '王五');
CREATE TABLE SC(S VARCHAR(10),C VARCHAR(10),score DECIMAL(18,1));
INSERT INTO SC VALUES('01' , '01' , 80);
INSERT INTO SC VALUES('01' , '02' , 90);
INSERT INTO SC VALUES('01' , '03' , 99);
INSERT INTO SC VALUES('02' , '01' , 70);
INSERT INTO SC VALUES('02' , '02' , 60);
INSERT INTO SC VALUES('02' , '03' , 80);
INSERT INTO SC VALUES('03' , '01' , 80);
INSERT INTO SC VALUES('03' , '02' , 80);
INSERT INTO SC VALUES('03' , '03' , 80);
INSERT INTO SC VALUES('04' , '01' , 50);
INSERT INTO SC VALUES('04' , '02' , 30);
INSERT INTO SC VALUES('04' , '03' , 20);
INSERT INTO SC VALUES('05' , '01' , 76);
INSERT INTO SC VALUES('05' , '02' , 87);
INSERT INTO SC VALUES('06' , '01' , 31);
INSERT INTO SC VALUES('06' , '03' , 34);
INSERT INTO SC VALUES('07' , '02' , 89);
INSERT INTO SC 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 a.*

,b.score '01课程'

,c.score '02课程'

FROM student a

INNER JOIN sc b

ON a.S = b.S AND b.C = '01'

INNER JOIN sc c

ON a.S = c.S AND c.C = '02'

WHERE b.score > c.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
--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 a.S

,a.Sname

,AVG(b.score) score_avg

FROM student a

INNER JOIN sc b

ON a.S = b.S

GROUP BY a.S

HAVING score_avg >= 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
--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

,a.Sname

,COUNT(b.C)

,SUM(b.score)

FROM student a

LEFT JOIN sc b

ON a.S = b.S

GROUP BY a.S

--6、查询"李"姓老师的数量

SELECT COUNT(1)

FROM teacher

WHERE Tname LIKE '李%'

--7、查询学过"张三"老师授课的同学的信息

SELECT distinct a.*

FROM student a

INNER JOIN sc b

ON a.S = b.S

INNER JOIN course c

ON b.C = c.C

INNER JOIN teacher d

ON c.T = d.T AND d.Tname = '张三'

或者

SELECT a.*

FROM student a

INNER JOIN sc b

ON a.S = b.S

INNER JOIN course c

ON b.C = c.C

INNER JOIN teacher d

ON c.T = d.T AND d.Tname = '张三'

GROUP BY 1,2,3
--8、查询没学过"张三"老师授课的同学的信息

SELECT a.*

FROM student a

WHERE a.S NOT in (

SELECT S

FROM sc b

INNER JOIN course c

ON b.C = c.C

INNER JOIN teacher d

ON d.T = c.T AND d.Tname = '张三'

)

或

SELECT a.*

FROM student a

WHERE not EXISTS (

SELECT 1

FROM sc b

INNER JOIN course c

ON b.C = c.C

INNER JOIN teacher d

ON d.T = c.T AND d.Tname = '张三'

WHERE a.S = b.S

)

--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

INNER JOIN sc b

ON a.S = b.S AND b.C = '01'

INNER JOIN sc c

ON a.S = c.S AND c.C = '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

LEFT JOIN sc b

ON a.S = b.S AND b.C = '01'

LEFT JOIN sc c

ON a.S = c.S AND c.C = '02'

WHERE b.C = '01' AND c.C IS NULL

SELECT *

FROM student a

INNER JOIN sc b

ON a.S = b.S AND b.C = '01'

INNER JOIN sc c

ON a.S = c.S AND c.C = '02'

LEFT JOIN

INNER JOIN

--11、查询没有学全所有课程的同学的信息

SELECT a.*

FROM student a

LEFT JOIN sc b

ON a.S = b.S

LEFT JOIN (

SELECT COUNT(1) course_count

FROM course

) c

ON 1=1

GROUP BY a.S

HAVING COUNT(b.C) < MIN(c.course_count)

--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 a.*

,b.C

FROM student a

INNER JOIN sc b

ON a.S = b.S

WHERE b.C IN (

SELECT b.C

FROM student a

INNER JOIN sc b

ON a.S = b.S AND a.S = '01'

)

或

SELECT a.*

,b.C

FROM student a

INNER JOIN sc b

ON a.S = b.S

WHERE b.C IN (

SELECT c.C

FROM sc c

WHERE c.S = '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

--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.Sname

FROM student a

WHERE NOT EXISTS (

SELECT b.S

,d.Tname

FROM sc b

INNER JOIN course c

ON b.C = c.C

INNER JOIN teacher d

ON c.T = d.T AND d.Tname = '张三'

WHERE a.S = b.S

)

--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,a.Sname, b.avg_score

FROM student a

INNER JOIN (

SELECT b.S

,AVG(b.score) avg_score

,COUNT(b.score) bjg_count

FROM sc b

WHERE b.score <= 60

GROUP BY b.S

HAVING bjg_count >= 2

) b

ON a.S = b.S

或

SELECT a.S

,a.Sname

,AVG(b.score)

FROM student a

LEFT JOIN sc b

ON a.S = b.S

GROUP BY a.S

,a.Sname

HAVING SUM(CASE WHEN b.score < 60 THEN 1 ELSE 0 END) >= 2

--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.score

FROM student a

INNER JOIN sc b

ON a.S = b.S AND b.C = '01'

WHERE b.score < 60

ORDER BY b.score DESC

或

SELECT a.*

,b.score

FROM student a

INNER JOIN sc b

ON a.s=b.s

WHERE

b.c='01'

AND b.score<60

ORDER BY b.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

,SUM(CASE WHEN b.C = '01' THEN b.score ELSE 0 END) AS s01

,SUM(CASE WHEN b.C = '02' THEN b.score ELSE 0 END) AS s02

,SUM(CASE WHEN b.C = '03' THEN b.score ELSE 0 END) AS s03

,AVG(b.score) avg_score

FROM student a

LEFT JOIN sc b

ON a.S = b.S

GROUP BY a.S

ORDER BY avg_score 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
--及格为>=60，中等为：70-80，优良为：80-90，优秀为：>=90

select b.c

,b.cname

,max(a.score)

,min(a.score)

,avg(a.score)

,SUM(CASE WHEN a.score>=60 THEN 1 ELSE 0 END)/COUNT(1) AS 及格率

,SUM(CASE WHEN a.score>=70 AND a.score<80 THEN 1 ELSE 0 END)/COUNT(1) AS 中等率

,SUM(CASE WHEN a.score>=80 AND a.score<90 THEN 1 ELSE 0 END)/COUNT(1) AS 优良率

,SUM(CASE WHEN a.score>=90 THEN 1 ELSE 0 END)/COUNT(1) AS 优秀率

from sc a

left join course b

on a.c = b.c

group by b.c

--19、按各科成绩进行排序，并显示排名

SELECT a.C

,a.S

,a.score

,COUNT(b.C)+1 rank

FROM sc a

LEFT JOIN sc b

ON a.C = b.C AND b.score > a.score

GROUP BY a.C

,a.S

,a.score DESC

--20、查询学生的总成绩并进行排名

SELECT b.S

, b.sum_score

, COUNT(1) as pm

FROM (

SELECT a.S

,SUM(a.score) sum_score

FROM sc a

GROUP BY a.S

) b

LEFT JOIN (

SELECT a.S

,SUM(a.score) sum_score

FROM sc a

GROUP BY a.S

) c

ON c.sum_score >= b.sum_score

GROUP BY b.S

, b.sum_score

ORDER BY sum_score desc

--21、查询不同老师所教不同课程平均分从高到低显示

SELECT c.T

,c.Tname

,b.C

,AVG(a.score) avg_score

FROM sc a

LEFT JOIN course b

ON a.C = b.C

LEFT JOIN teacher c

ON b.T = c.T

GROUP BY c.T

,c.Tname

,b.C

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

select a.*

,b.C

,b.score

,b.rank

from student a,

(

SELECT a.C

,a.S

,a.score

,SUM(case when b.score>a.score then 1 else 0 end)+1 rank

FROM sc a

LEFT JOIN sc b

ON a.C = b.C

GROUP BY a.C

,a.S

,a.score desc

where a.S = b.S and b.rank in (2,3)

--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 b.c

,b.cname

,count(1)

,sum(case when a.score < 60 then 1 else 0 end) "[0-60]"

,sum(case when a.score >= 60 and a.score <70 then 1 else 0 end) "[70-60]"

,sum(case when a.score >= 70 and a.score <85 then 1 else 0 end) "[85-70]"

,sum(case when a.score >= 85 then 1 else 0 end) "[100-85]"

,sum(case when a.score < 60 then 1 else 0 end) / count(1) "[0-60]%"

,sum(case when a.score >= 60 and a.score <70 then 1 else 0 end) / count(1) "[70-60]%"

,sum(case when a.score >= 70 and a.score <85 then 1 else 0 end) / count(1) "[85-70]%"

,sum(case when a.score >= 85 then 1 else 0 end) / count(1) "[100-85]%"

from course b

inner join sc a

on a.c = b.c

group by b.c

,b.cname

--24、查询学生平均成绩及其名次

select b.s

,b.avg_score

,count(1) pm

from (

select a.s

,avg(a.score) avg_score

from sc a

group by a.s

left join (

select a.s

,avg(a.score) avg_score

from sc a

group by a.s

on c.avg_score >= b.avg_score

group by b.s

,b.avg_score

order by b.avg_score desc

--25、查询各科成绩前三名的记录

select k.c

,k.s

,k.score

,k.rank

from (select a.c

,a.s

,a.score

,count(1) rank

from sc a

left join sc b

on a.c = b.c and b.score > a.score

group by a.c

,a.s

,a.score desc

) k

where k.rank <= 3

--26、查询每门课程被选修的学生数

select a.c

,count(1) stu_count

from sc a

group by a.c

--27、查询出只有两门课程的全部学生的学号和姓名

select b.s

,b.sname

from student b

select a.s

,count(a.c) c_count

from sc a

group by a.s

having c_count = 2

where b.s = c.s

--28、查询男生、女生人数

select sum(case when a.Ssex = '男'then 1 else 0 end) 男

,sum(case when a.Ssex = '女'then 1 else 0 end) 女

from student a

--29、查询名字中含有"风"字的学生信息

select *

from student

where Sname like '%风%'

--30、查询同名同性学生名单，并统计同名人数

select a.*

,count(1) stu_count

from student a

group by a.sname

,a.ssex

having stu_count > 1

--31、查询1990年出生的学生名单(注：Student表中Sage列的类型是datetime)

select a.*

from student a

where a.sage like '1990%'

或

select a.*

from student a

where year(a.sage)=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

select a.c

,avg(a.score) avg_score

from sc a

group by a.c

order by avg_score desc

,a.c

--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

,a.sname

,avg(b.score) avg_score

from student a

left join sc b

on a.s = b.s

group by a.s

,a.sname

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.sname

,b.score

from student a

left join sc b

on a.s = b.s

left join course c

on b.c = c.c

where c.cname = '数学' and b.score < 60

--35、查询所有学生的课程及分数情况；

select a.s

,a.c

,a.score

,b.*

from sc a

left join course b

on a.c = b.c

--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.sname

,c.cname

,b.score

from student a

left join sc b

on a.s = b.s

left join course c

on b.c = c.c

where b.score >= 70

--37、查询不及格的课程

select a.c

,a.score

,b.*

from sc a

left join course b

on a.c = b.c

where a.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

,a.sname

from student a

left join sc b

on a.s = b.s

where b.c = '01' and b.score >= 80

--39、求每门课程的学生人数

select a.c

,count(1) c_count

from sc a

group by a.c

,a.s

--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 a.*

,b.score

from student a

left join sc b

on a.s = b.s

left join course c

on b.c = c.c

left join teacher d

on c.t = d.t

where d.tname = "张三"

group by b.c

having b.score = max(b.score)

--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 a.s

,a.c

,a.score

from sc a

left join sc b

on a.s = b.s

where a.score = b.score and a.c != b.c

group by a.s

,a.c

--42、查询每门功成绩最好的前两名

select d.c

,d.s

,d.rank

from (

select a.c

,a.s

,a.score

,sum(case when b.score > a.score then 1 else 0 end)+1 rank

from sc a

left join sc b

on a.s = b.s

group by a.c

,a.s

) d

where d.rank <= 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 a.c

,count(1) c_num

from sc a

group by a.c

having c_num > 5

order by c_num desc

,a.c

--44、检索至少选修两门课程的学生学号

select a.s

,count(a.s) c_num

from sc a

group by a.s

having c_num >= 2

--45、查询选修了全部课程的学生信息

select a.*

,count(b.c) sc_num

from student a

left join sc b

on a.s = b.s

group by a.s

having sc_num = (select count(1) c_num from course)

--46、查询各学生的年龄

select s

,year(now()) - year(sage) stu_age

from student

--47、查询本周过生日的学生

select a.sname

from (select sname

,weekofyear(sage) week_age

,weekofyear(now()) week_now

from student) a

where a.week_age = a.week_now

--48、查询下周过生日的学生

select a.sname

from (select sname

,weekofyear(sage) week_age

,weekofyear(now()) week_now

from student) a

where a.week_age = a.week_now+1

--49、查询本月过生日的学生

select a.sname

from (select sname

,month(sage) month_age

,month(now()) month_now

from student) a

where a.month_age = a.month_now

--50、查询下月过生日的学生

select a.sname

from (select sname

,month(sage) month_age

,month(now()) month_now

from student) a

where a.month_age = a.month_now+1