SQL练习

 

目录

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

3.查询在 SC 表存在成绩的学生信息

4.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(没成绩的显示为 null )

5.查询「李」姓老师的数量

6.查询学过「张三」老师授课的同学的信息

7.查询没有学全所有课程的同学的信息

8.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

9.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

10.查询没学过"张三"老师讲授的任一门课程的学生姓名

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11.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

12.检索" 01 "课程分数小于 60，按分数降序排列的学生信息

13.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

14.查询各科成绩最高分、最低分和平均分：

15.按各科成绩进行排序，并显示排名， Score 重复时保留名次空缺

16.查询学生的总成绩，并进行排名，总分重复时保留名次空缺

17.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]，[60-0] 及所占百分比

18.查询各科成绩前三名的记录

19.查询每门课程被选修的学生数

20.查询出只选修两门课程的学生学号和姓名

21.查询男生、女生人数

22.查询名字中含有「风」字的学生信息

23.查询同名同性学生名单，并统计同名人数

24.查询 1990 年出生的学生名单

25.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

26.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

27.查询课程名称为「数学」，且分数低于 60 的学生姓名和分数

28.查询所有学生的课程及分数情况（存在学生没成绩，没选课的情况）

29.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

30.查询不及格的课程

31.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

32.求每门课程的学生人数

33.成绩不重复，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

34.成绩有重复的情况下，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

35.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

36.查询每门功成绩最好的前两名

37.统计每门课程的学生选修人数（超过 5 人的课程才统计）。

38.检索至少选修两门课程的学生学号

39.查询选修了全部课程的学生信息

40.查询各学生的年龄，只按年份来算

41.按照出生日期来算，当前月日 < 出生年月的月日则，年龄减一

42.查询本周过生日的学生

43.查询下周过生日的学生

44.查询本月过生日的学生

45.查询下月过生日的学生

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数据表介绍
--1.学生表
Student(SId,Sname,Sage,Ssex)
--SId 学生编号,Sname 学生姓名,Sage 出生年月,Ssex 学生性别
--2.课程表
Course(CId,Cname,TId)
--CId 课程编号,Cname 课程名称,TId 教师编号
--3.教师表
Teacher(TId,Tname)
--TId 教师编号,Tname 教师姓名
--4.成绩表
SC(SId,CId,score)
--SId 学生编号,CId 课程编号,score 分数学生表 Student
create table Student(SId 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' , '1990-12-20' , '男');
insert into Student values('04' , '李云' , '1990-12-06' , '男');
insert into Student values('05' , '周梅' , '1991-12-01' , '女');
insert into Student values('06' , '吴兰' , '1992-01-01' , '女');
insert into Student values('07' , '郑竹' , '1989-01-01' , '女');
insert into Student values('09' , '张三' , '2017-12-20' , '女');
insert into Student values('10' , '李四' , '2017-12-25' , '女');
insert into Student values('11' , '李四' , '2012-06-06' , '女');
insert into Student values('12' , '赵六' , '2013-06-13' , '女');
insert into Student values('13' , '孙七' , '2014-06-01' , '女');科目表 Course
create table Course(CId varchar(10),Cname nvarchar(10),TId 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');教师表 Teacher
create table Teacher(TId 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');成绩表 SC
create table SC(SId varchar(10),CId 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 s.*, sc1.score as score1, sc2.score as score2
from student s
join sc sc1 on s.sid = sc1.sid and sc1.cid = '01'
join sc sc2 on s.sid = sc2.sid and sc2.cid = '02'
where sc1.score > sc2.score;1.1查询同时存在" 01 "课程和" 02 "课程的情况
select s.*, sc1.score as score1, sc2.score as score2
from student s
join sc sc1 on s.sid = sc1.sid and sc1.cid = '01'
join sc sc2 on s.sid = sc2.sid and sc2.cid = '02';1.2查询存在" 01 "课程但可能不存在" 02 "课程的情况(不存在时显示为 null )
select s.*, sc1.score as score1, sc2.score as score2
from student s
join sc sc1 on s.sid = sc1.sid and sc1.cid = '01'
left join sc sc2 on s.sid = sc2.sid and sc2.cid = '02';1.3查询不存在" 01 "课程但存在" 02 "课程的情况
select s.*, sc2.score as '02课程成绩'
from student s
join sc sc2 on s.sid = sc2.sid and sc2.cid = '02'
where not exists (select 1 from sc sc1 where sc1.sid = s.sid and sc1.cid = '01'
);

2.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 s.sid, s.sname, avg(sc.score) as avg_score
from student s
join sc on s.sid = sc.sid
group by s.sid, s.sname
having avg(sc.score) >= 60
order by avg_score desc;

3.查询在 SC 表存在成绩的学生信息

select s.*
from student s
where s.sid in (select distinct sid from sc
);

 

4.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(没成绩的显示为 null )

select s.sid, s.sname, count(sc.cid), sum(sc.score)
from student s
left join sc on s.sid = sc.sid
group by s.sid, s.sname
order by s.sid;4.1 查有成绩的学生信息
select s.sid, s.sname, count(sc.cid), sum(sc.score)
from student s
inner join sc on s.sid = sc.sid
group by s.sid, s.sname
order by s.sid;

5.查询「李」姓老师的数量

select count(*) as '李姓老师数量'
from teacher
where tname like '李%';

 

6.查询学过「张三」老师授课的同学的信息

select distinct s.*
from student s
join sc on s.sid = sc.sid
join course c on sc.cid = c.cid
join teacher t on c.tid = t.tid
where t.tname = '张三';

 

7.查询没有学全所有课程的同学的信息

select s.*
from student s
where s.sid not in (select sid from scgroup by sidhaving count(distinct cid) = (select count(*) from course)
);

8.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

select distinct s.*
from student s
join sc on s.sid = sc.sid
where sc.cid in (select cid from sc where sid = '01'
) and s.sid != '01';

 

9.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 s.*
from student s
where s.sid in (select sid from scwhere sid != '01'group by sidhaving group_concat(cid order by cid) = (select group_concat(cid order by cid)from scwhere sid = '01')
);

 

10.查询没学过"张三"老师讲授的任一门课程的学生姓名

select sname
from student
where sid not in (select distinct sc.sidfrom scjoin course c on sc.cid = c.cidjoin teacher t on c.tid = t.tidwhere t.tname = '张三'
);

11.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 s.sid, s.sname, avg(sc.score) as avg_score
from student s
join sc on s.sid = sc.sid
where sc.score < 60
group by s.sid, s.sname
having count(*) >= 2;

12.检索" 01 "课程分数小于 60，按分数降序排列的学生信息

select s.*, sc.score
from student s
join sc on s.sid = sc.sid
where sc.cid = '01' and sc.score < 60
order by sc.score desc;

 

13.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 sc 
left join (select sid,avg(score) as avscore from sc group by sid)r 
on sc.sid = r.sid
order by avscore desc;

 

14.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

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 sc.CId ,max(sc.score)as 最高分,min(sc.score)as 最低分,avg(sc.score)as 平均分,count(*)as 选修人数,sum(case when sc.score>=60 then 1 else 0 end )/count(*)as 及格率,sum(case when sc.score>=70 and sc.score<80 then 1 else 0 end )/count(*)as 中等率,sum(case when sc.score>=80 and sc.score<90 then 1 else 0 end )/count(*)as 优良率,sum(case when sc.score>=90 then 1 else 0 end )/count(*)as 优秀率 
from sc
group by sc.cid
order by count(*) desc, sc.cid asc;

15.按各科成绩进行排序，并显示排名， Score 重复时保留名次空缺

select sc.cid, course.cname, sc.sid, student.sname, sc.score,dense_rank() over (partition by sc.cid order by sc.score desc) as '排名'
from sc
join student on sc.sid = student.sid
join course on sc.cid = course.cid
order by sc.cid, '排名';15.1 按各科成绩进行排序，并显示排名， Score 重复时合并名次
selectsc.cid,course.cname,sc.sid,student.sname,sc.score,RANK() OVER (PARTITION BY sc.cid ORDER BY sc.score DESC) AS '排名'
from sc
join student on sc.sid = student.sid
join course on sc.cid = course.cid
order by sc.cid, '排名';

16.查询学生的总成绩，并进行排名，总分重复时保留名次空缺

SELECT s.sid,s.sname,COALESCE(SUM(sc.score), 0) AS '总成绩',DENSE_RANK() OVER (ORDER BY COALESCE(SUM(sc.score), 0) DESC) AS '排名'
FROM student s
LEFT JOIN sc ON s.sid = sc.sid
GROUP BY s.sid, s.sname
ORDER BY '排名';16.1 查询学生的总成绩，并进行排名，总分重复时不保留名次空缺
SELECT s.sid,s.sname,COALESCE(SUM(sc.score), 0) AS '总成绩',RANK() OVER (ORDER BY COALESCE(SUM(sc.score), 0) DESC) AS '排名'
FROM student s
LEFT JOIN sc ON s.sid = sc.sid
GROUP BY s.sid, s.sname
ORDER BY '排名';

17.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]，[60-0] 及所占百分比

select course.cid,course.cname,sum(case when sc.score between 85 and 100 then 1 else 0 end) as '100-85',round(sum(case when sc.score between 85 and 100 then 1 else 0 end)*100.0/count(*),2) as '100-85',sum(case when sc.score between 70 and 84 then 1 else 0 end) as '85-70',round(sum(case when sc.score between 70 and 84 then 1 else 0 end)*100.0/count(*),2) as '85-70',sum(case when sc.score between 60 and 69 then 1 else 0 end) as '[70-60]人数',round(sum(case when sc.score between 60 and 69 then 1 else 0 end)*100.0/count(*),2) as '70-60',sum(case when sc.score < 60 then 1 else 0 end) as '60-0',round(sum(case when sc.score < 60 then 1 else 0 end)*100.0/count(*),2) as '60-0'
from course
left join sc on course.cid = sc.cid
group by course.cid, course.cname;

18.查询各科成绩前三名的记录

select * from sc
where (select count(*) from sc as a where sc.cid = a.cid and sc.score<a.score)< 3
order by cid asc, sc.score desc;

 

19.查询每门课程被选修的学生数

select cid, count(sid) from sc 
group by cid;

 

20.查询出只选修两门课程的学生学号和姓名

select student.sid, student.sname
from student
join (select sidfrom scgroup by sidhaving count(cid) = 2
) t on student.sid = t.sid;

 

21.查询男生、女生人数

select ssex, count(*) as '人数' from student group by ssex;

22.查询名字中含有「风」字的学生信息

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

 

23.查询同名同性学生名单，并统计同名人数

select sname, count(*) from student
group by sname
having count(*)>1;

 

24.查询 1990 年出生的学生名单

select * from student where year(sage) = 1990;

 

25.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 course.cid,course.cname,round(avg(sc.score),2) as avg_score
from course
left join sc on course.cid = sc.cid
group by course.cid, course.cname
order by avg_score desc, course.cid asc;

 

26.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 student.sid,student.sname,round(avg(sc.score),2) as avg_score
from student
join sc on student.sid = sc.sid
group by student.sid, student.sname
having avg(sc.score) >= 85;

 

27.查询课程名称为「数学」，且分数低于 60 的学生姓名和分数

select student.sname, sc.score
from student
join sc on student.sid = sc.sid
join course on sc.cid = course.cid
where course.cname = '数学' and sc.score < 60;

 

28.查询所有学生的课程及分数情况（存在学生没成绩，没选课的情况）

select student.sid,student.sname,course.cname,sc.score
from student
left join sc on student.sid = sc.sid
left join course on sc.cid = course.cid
order by student.sid, course.cid;

 

29.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 student.sname, course.cname, sc.score 
from student, course, sc
where sc.score>70 and student.sid = sc.sid and sc.cid = course.cid;

30.查询不及格的课程

select student.sid, student.sname, course.cname, sc.score
from student
join sc on student.sid = sc.sid
join course on sc.cid = course.cid
where sc.score < 60;

31.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 student.sid,student.sname 
from student,sc
where cid="01"
and score>=80
and student.sid = sc.sid;

 

32.求每门课程的学生人数

select course.cid,course.cname,count(sc.sid) as student_count
from course
left join sc on course.cid = sc.cid
group by course.cid, course.cname;

 

33.成绩不重复，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 student.*, sc.score
from student
join sc on student.sid = sc.sid
join course on sc.cid = course.cid
join teacher on course.tid = teacher.tid
where teacher.tname = '张三'
order by sc.score desc
limit 1;

 

34.成绩有重复的情况下，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 student.*,sc.score
from student
join sc on student.sid = sc.sid
join course on sc.cid = course.cid
join teacher on course.tid = teacher.tid
where teacher.tname = '张三'and sc.score = (select max(score) from sc join course on sc.cid = course.cidjoin teacher on course.tid = teacher.tidwhere teacher.tname = '张三');

35.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 distincta.sid,student.sname,a.cid as cid1,b.cid as cid2,a.score
from sc a
join sc b on a.sid = b.sid and a.score = b.score and a.cid < b.cid
join student on a.sid = student.sid;

36.查询每门功成绩最好的前两名

select sc.cid, course.cname, sc.sid, student.sname, sc.score
from sc
join student on sc.sid = student.sid
join course on sc.cid = course.cid
where (select count(*) from sc sc2 where sc2.cid = sc.cid and sc2.score >= sc.score) <= 2
order by sc.cid, sc.score desc;

37.统计每门课程的学生选修人数（超过 5 人的课程才统计）。

select course.cid, course.cname, count(sc.sid) as student_count
from course
join sc on course.cid = sc.cid
group by course.cid, course.cname
having count(sc.sid) > 5;

38.检索至少选修两门课程的学生学号

select sid from sc group by sid having count(cid) >= 2;

39.查询选修了全部课程的学生信息

select student.*
from student
where not exists (select cid from coursewhere not exists (select 1 from sc where sc.sid = student.sid and sc.cid = course.cid)
);

40.查询各学生的年龄，只按年份来算

select sid, sname, year(current_date) - year(sage) as age from student;

41.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 sid,sname,year(current_date) - year(sage) - case when month(current_date) < month(sage) then 1when month(current_date) = month(sage) and day(current_date) < day(sage) then 1else 0end as exact_age
from student;

42.查询本周过生日的学生

select * from student where weekofyear(sage) = weekofyear(current_date);

43.查询下周过生日的学生

select *
from student
where weekofyear(sage) = weekofyear(current_date) + 1;

44.查询本月过生日的学生

select *
from student
where month(sage) = month(current_date);

45.查询下月过生日的学生

select *
from student
where month(sage) = month(current_date) + 1 or (month(current_date) = 12 and month(sage) = 1);