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);
练习题目
-
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 student as a
right join sc as b
on a.sid=b.sid
inner join sc as c
on a.sid=c.sid and b.cid=01 and c.cid=02
where b.score>c.score;
1.1查询同时存在" 01 "课程和" 02 "课程的情况
select *
from sc as a
inner join sc as b
on a.sid=b.sid and a.cid='01' and b.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 *
from sc as a
left join sc as b
on a.sid=b.sid and b.cid='02'
where a.cid = '01';
1.3查询不存在" 01 "课程但存在" 02 "课程的情况
select *
from sc
where sid not in (select sid from sc where cid='01')
and cid ='02';
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 a.sid,a.sname,avg(b.score) as s_avg
from student as a
right join sc as b
on a.sid=b.sid
group by b.sid
having s_avg>60;
3.查询在 SC 表存在成绩的学生信息
select a.*
from student as a
right join sc as b
on a.sid=b.sid
group by b.sid;
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 a.sid,a.sname,count(b.cid) as c_sum,sum(b.score) as s_sum
from student as a
left join sc as b
on a.sid=b.sid
group by a.sid;
4.1 查有成绩的学生信息
select * from student
where sid in(select distinct sid from sc);
5.查询「李」姓老师的数量
select count(*)
from teacher
where tname like '李%';
6.查询学过「张三」老师授课的同学的信息
select student.*
from teacher,course,sc,student
where teacher.tname = '张三'
and teacher.tid=course.tid
and course.cid=sc.cid
and sc.sid=student.sid;
7.查询没有学全所有课程的同学的信息
select a.*,count(cid) as c_count
from student as a
inner join sc as b
on a.sid=b.sid
group by a.sid
having c_count<(select count(cid) 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 cid from sc where sid = '01';
select * from student where sid in(
select distinct sid from sc
where cid in(select cid from sc where 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 * from student where sid in(
select a.sid from (select sid,group_concat(cid order by cid) as courses
from sc group by sid) as a
inner join (select sid,group_concat(cid order by cid) as courses
from sc group by sid having sid='01') as b
on a.sid != 1 and a.courses = b.courses);
10.查询没学过"张三"老师讲授的任一门课程的学生姓名
select distinct sname from student where sid not in(
select sid from sc where cid in(
select a.cid from course as a
inner join teacher as b
on a.tid=b.tid
where b.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 student.SId, student.Sname,b.avg
from student RIGHT JOIN
(select sid, AVG(score) as avg from sc
where sid in (
select sid from sc
where score<60
GROUP BY sid
HAVING count(score)>1)
GROUP BY sid) b on student.sid=b.sid;
12.检索" 01 "课程分数小于 60，按分数降序排列的学生信息
select student.*, sc.score from student, sc
where student.sid = sc.sid
and sc.score < 60
and cid = "01"
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
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 a.cid, a.sid, a.score, count(b.score)+1 as rank
from sc as a
left join sc as b
on a.score<b.score and a.cid = b.cid
group by a.cid, a.sid,a.score
order by a.cid, rank ASC;
15.1 按各科成绩进行排序，并显示排名， Score 重复时合并名次
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
set @crank=0;
select q.sid, total, @crank := @crank +1 as rank from(
select sc.sid, sum(sc.score) as total from sc
group by sc.sid
order by total desc)q;
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
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.cname, course.cid,
sum(case when sc.score<=100 and sc.score>85 then 1 else 0 end) as "[100-85]",
sum(case when sc.score<=85 and sc.score>70 then 1 else 0 end) as "[85-70]",
sum(case when sc.score<=70 and sc.score>60 then 1 else 0 end) as "[70-60]",
sum(case when sc.score<=60 and sc.score>0 then 1 else 0 end) as "[60-0]"
from sc left join course
on sc.cid = course.cid
group by sc.cid;
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,sc where student.sid=sc.sid group by sid having count(cid)=2;
21.查询男生、女生人数
select ssex,count(*) 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
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 cid,avg(score) from sc group by cid order by avg(score) desc,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.sname,student.sid,avg(score) from student,sc where student.sid=sc.sid having avg(score)>=85 group by student.sid;
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 score,sname from student,sc,course where student.sid=sc.sid and sc.cid=course.cid and cname='数学' and 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.sname, cid, score from studentleft join sc on student.sid = sc.sid;
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 sname,cname,score from student,sc,course where student.sid=sc.sid and sc.cid=course.cid and score>70;
30.查询不及格的课程
select cname from sc,course where sc.cid=course.cid and 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,course where student.sid=sc.sid and sc.cid=course.cid and course.cid='01' and score>=80;
32.求每门课程的学生人数
select count(student.sid),cname from course,student,sc where student.sid=sc.sid and sc.cid=course.cid group by 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 distinct * from student,sc,teacher,course where student.sid=sc.sid and teacher.tid=course.tid and sc.cid=course.cid and teacher.tname='张三' having max(score);
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 * from student,sc,teacher,course where student.sid=sc.sid and teacher.tid=course.tid and sc.cid=course.cid and teacher.tname='张三' having max(score);
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）。
select count(sid) from sc group by cid having count(sid)>=5;
38.检索至少选修两门课程的学生学号
select student.sid from student,sc where student.sid=sc.sid 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,sc where student.sid=sc.sid group by sid having count(cid)=3 ;
40.查询各学生的年龄，只按年份来算
select 2023-year(sage),sname 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
42.查询本周过生日的学生
select * from student where weekofyear(sage)=weekofyear(curdate());
43.查询下周过生日的学生
select * from student where weekofyear(sage)=weekofyear(curdate())+1;
44.查询本月过生日的学生
select * from student where month(sage)=month(curdate());
45.查询下月过生日的学生
select * from student where month(sage)=month(curdate())+1;