MySQL---经典SQL练习题
MySQL---经典50道练习题
-
- 素材:
- 练习题目：
- 解题：
素材:
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
1.学生表 Student
create table Student(SId varchar(10),Sname varchar(10),Sage datetime,Ssex varchar(10));
插入数据：
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' , '1990-12-20' , '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');
2.科目表 Course
create table Course(CId varchar(10),Cname nvarchar(10),TId varchar(10));
插入数据：
insert into Course values('01' , '语文' , '02');
insert into Course values('02' , '数学' , '01');
insert into Course values('03' , '英语' , '03');
3.教师表 Teacher
create table Teacher(TId varchar(10),Tname varchar(10));
插入数据：
insert into Teacher values('01' , '张三');
insert into Teacher values('02' , '李四');
insert into Teacher values('03' , '王五');
4.成绩表 SC
create table SC(SId varchar(10),CId varchar(10),score decimal(18,1));
插入数据：
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：
1.查询" 01 "课程比" 02 "课程成绩高的学生的信息及课程分数
1.1查询同时存在" 01 "课程和" 02 "课程的情况
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 )
1.3查询不存在" 01 "课程但存在" 02 "课程的情况
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 )
4.1 查有成绩的学生信息
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
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：
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
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
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
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
解题：
1.首先创建数据库db_test50;
mysql> use db_test50;
Database changed
2.然后根据题目创建四张表（可复制粘贴上方素材）
2.1.学生表 Student(SId,Sname,Sage,Ssex)
mysql> create table Student(SId varchar(10),Sname varchar(10),Sage datetime,Ssex varchar(10));I
Query OK, 0 rows affected (0.06 sec)
2.2.课程表 Course(CId,Cname,TId)
mysql> create table Course(CId varchar(10),Cname nvarchar(10),TId varchar(10));
Query OK, 0 rows affected, 1 warning (0.06 sec)
2.3.教师表Teacher(TId,Tname)
mysql> create table Teacher(TId varchar(10),Tname varchar(10));
Query OK, 0 rows affected (0.03 sec)
2.4.成绩表SC(SId,CId,score)
mysql> create table SC(SId varchar(10),CId varchar(10),score decimal(18,1));
Query OK, 0 rows affected (0.02 sec)
3.给各个表中插入相应的数据（可复制粘贴上方素材）
3.1.学生表 Student(SId,Sname,Sage,Ssex)
mysql> insert into Student values('01' , '赵雷' , '1990-01-01' , '男');
Query OK, 1 row affected (0.01 sec)
mysql> insert into Student values('02' , '钱电' , '1990-12-21' , '男');
Query OK, 1 row affected (0.01 sec)
mysql> insert into Student values('03' , '孙风' , '1990-12-20' , '男');
Query OK, 1 row affected (0.00 sec)
mysql> insert into Student values('04' , '李云' , '1990-12-06' , '男');
Query OK, 1 row affected (0.00 sec)
mysql> insert into Student values('05' , '周梅' , '1991-12-01' , '女');
Query OK, 1 row affected (0.00 sec)
mysql> insert into Student values('06' , '吴兰' , '1992-01-01' , '女');
Query OK, 1 row affected (0.00 sec)
mysql> insert into Student values('07' , '郑竹' , '1989-01-01' , '女');
Query OK, 1 row affected (0.01 sec)
mysql> insert into Student values('09' , '张三' , '2017-12-20' , '女');
Query OK, 1 row affected (0.00 sec)
mysql> insert into Student values('10' , '李四' , '2017-12-25' , '女');
Query OK, 1 row affected (0.00 sec)
mysql> insert into Student values('11' , '李四' , '2012-06-06' , '女');
Query OK, 1 row affected (0.01 sec)
mysql> insert into Student values('12' , '赵六' , '2013-06-13' , '女');
Query OK, 1 row affected (0.00 sec)
mysql> insert into Student values('13' , '孙七' , '2014-06-01' , '女');
Query OK, 1 row affected (0.00 sec)
3.2.课程表 Course(CId,Cname,TId)
mysql> insert into Course values('01' , '语文' , '02');
Query OK, 1 row affected (0.01 sec)
mysql> insert into Course values('02' , '数学' , '01');
Query OK, 1 row affected (0.02 sec)
mysql> insert into Course values('03' , '英语' , '03');
Query OK, 1 row affected (0.02 sec)
3.3.教师表Teacher(TId,Tname)
mysql> insert into Teacher values('01' , '张三');
Query OK, 1 row affected (0.01 sec)
mysql> insert into Teacher values('02' , '李四');
Query OK, 1 row affected (0.00 sec)
mysql> insert into Teacher values('03' , '王五');
Query OK, 1 row affected (0.00 sec)
3.4.成绩表SC(SId,CId,score)
mysql> insert into SC values('01' , '01' , 80);
Query OK, 1 row affected (0.01 sec)
mysql> insert into SC values('01' , '02' , 90);
Query OK, 1 row affected (0.01 sec)
mysql> insert into SC values('01' , '03' , 99);
Query OK, 1 row affected (0.01 sec)
mysql> insert into SC values('02' , '01' , 70);
Query OK, 1 row affected (0.00 sec)
mysql> insert into SC values('02' , '02' , 60);
Query OK, 1 row affected (0.01 sec)
mysql> insert into SC values('02' , '03' , 80);
Query OK, 1 row affected (0.00 sec)
mysql> insert into SC values('03' , '01' , 80);
Query OK, 1 row affected (0.00 sec)
mysql> insert into SC values('03' , '02' , 80);
Query OK, 1 row affected (0.00 sec)
mysql> insert into SC values('03' , '03' , 80);
Query OK, 1 row affected (0.00 sec)
mysql> insert into SC values('04' , '01' , 50);
Query OK, 1 row affected (0.00 sec)
mysql> insert into SC values('04' , '02' , 30);
Query OK, 1 row affected (0.00 sec)
mysql> insert into SC values('04' , '03' , 20);
Query OK, 1 row affected (0.00 sec)
mysql> insert into SC values('05' , '01' , 76);
Query OK, 1 row affected (0.03 sec)
mysql> insert into SC values('05' , '02' , 87);
Query OK, 1 row affected (0.03 sec)
mysql> insert into SC values('06' , '01' , 31);
Query OK, 1 row affected (0.00 sec)
mysql> insert into SC values('06' , '03' , 34);
Query OK, 1 row affected (0.01 sec)
mysql> insert into SC values('07' , '02' , 89);
Query OK, 1 row affected (0.01 sec)
mysql> insert into SC values('07' , '03' , 98);
Query OK, 1 row affected (0.00 sec)
至此，数据库和表都创建完成，并且插入各个数据，最后，开始查询：
1.查询" 01 “课程比” 02 "课程成绩高的学生的信息及课程分数
mysql> select * from (
-> select t1.SId, class1, class2
-> from
-> (SELECT SId, score as class1 FROM sc WHERE sc.CId = '01') AS t1,
->(SELECT SId, score as class2 FROM sc WHERE sc.CId = '02') AS t2
-> where t1.SId = t2.SId and t1.class1 > t2.class2
-> ) r
-> LEFT JOIN Student
-> ON Student.SId = r.SId;
2查询同时存在" 01 “课程和” 02 "课程的情况
mysql> select * from
-> (select * from sc where sc.CId = '01') as t1,
-> (select * from sc where sc.CId = '02') as t2
-> where t1.SId = t2.SId;
3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 )
mysql> select * from
-> (select * from sc where sc.CId = '02') as t2
-> right join
-> (select * from sc where sc.CId = '01') as t1
-> on t1.SId = t2.SId;
4查询不存在" 01 “课程但存在” 02 "课程的情况
mysql> select * from sc
-> where sc.SId not in (
-> select SId from sc
-> where sc.CId = '01')
-> AND sc.CId= '02';
5.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
mysql> select s.SId,ss,Sname from(
-> select SId, AVG(score) as ss from sc
-> GROUP BY SId
-> HAVING AVG(score)> 60
-> )r left join
-> (select Student.SId, Student.Sname from
-> Student)s on s.SId = r.SId;
6.查询在 SC 表存在成绩的学生信息
mysql> select DISTINCT student.*
-> from student,sc
-> where student.SId=sc.SId;
7.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 )
mysql> select student.sid, student.sname,r.coursenumber,r.scoresum
-> from student,
-> (select sc.sid, sum(sc.score) as scoresum, count(sc.cid) as coursenumber from sc
-> group by sc.sid)r
-> where student.sid = r.sid;
8 查有成绩的学生信息
mysql> select * from student
-> where student.sid in (select sc.sid from sc);
9.查询「李」姓老师的数量
mysql> select count(*) from teacher where tname like '李%';
10.查询学过「张三」老师授课的同学的信息
mysql> select student.* from student,teacher,course,sc
-> where student.sid = sc.sid
-> and course.cid=sc.cid
-> and course.tid = teacher.tid
-> and tname = '张三';
11.查询没有学全所有课程的同学的信息
mysql> select * from student
-> where student.sid not in (
-> select sc.sid from sc
-> group by sc.sid
-> having count(sc.cid)= (select count(cid) from course)
-> );
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
mysql> select * from student
-> where student.sid in (
-> select sc.sid from sc
-> where sc.cid in
-> (select sc.cid from sc
-> where sc.sid = '01')
-> );
13.查询没学过"张三"老师讲授的任一门课程的学生姓名
mysql> select * from student
-> where student.sid not in(
-> select sc.sid from sc,course,teacher
-> Where sc.cid = course.cid
-> and course.tid = teacher.tid
-> and teacher.tname= "张三"
-> );
14.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
mysql> 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;
15.检索" 01 "课程分数小于 60，按分数降序排列的学生信息
mysql> select student.*, sc.score from student, sc
-> where student.sid = sc.sid
-> and sc.score < 60
-> and cid = "01"
-> ORDER BY sc.score DESC;
16.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
mysql> 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;
17.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
mysql> 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;
18.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
mysql> select c.cid as 课程编号, c.cname as 课程名称, A.*
-> from course as c,
-> (select cid,
-> sum(case when score >= 85 then 1 else 0 end)/count(*) as 100_85,
-> sum(case when score >= 70 and score < 85 then 1 else 0 end)/count(*) as 85_70,
-> sum(case when score >= 60 and score < 70 then 1 else 0 end)/count(*) as 70_60,
-> sum(case when score < 60 then 1 else 0 end)/count(*) as 60_0
-> from sc group by cid) as A
-> where c.cid = A.cid;
19.查询各科成绩前三名的记录
mysql> select * from sc
-> where (
-> select count(*) from sc as a
-> where sc.cid = a.cid and sc.score )< 3
-> order by cid asc, sc.score desc;
20.查询每门课程被选修的学生数
mysql> select cid, count(sid) from sc
-> group by cid;
21.查询出只选修两门课程的学生学号和姓名
mysql> select student.sid, student.sname from student
-> where student.sid in
-> (select sc.sid from sc
-> group by sc.sid
-> having count(sc.cid)=2
-> );
22.查询男生、女生人数
mysql> select ssex, count(*) from student group by ssex;
23.查询名字中含有「风」字的学生信息
mysql> select * from student where student.Sname like '%风%';
24.查询同名同性学生名单，并统计同名人数
mysql> select sname, count(*) from student
-> group by sname
-> having count(*)>1;
25.查询 1990 年出生的学生名单
mysql> select * from student where YEAR(student.Sage)=1990;
26.查询课程名称为「数学」，且分数低于 60 的学生姓名和分数
mysql> select student.sname, sc.score from student, sc, course
-> where student.sid = sc.sid
-> and course.cid = sc.cid
-> and course.cname = "数学"
-> and sc.score < 60;
27.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）
mysql> select student.sname, cid, score from student
-> left join sc
-> on student.sid = sc.sid;
28.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
mysql> 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;
29.查询不及格的课程
mysql> select cid from sc
-> where score< 60
-> group by cid;
30.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
mysql> select student.sid,student.sname
-> from student,sc
-> where cid="01"
-> and score>=80
-> and student.sid = sc.sid;
31.求每门课程的学生人数
mysql> select sc.CId,count(*) as 学生人数 from sc
-> GROUP BY sc.CId;
32.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
mysql> select student.*, sc.score, sc.cid from student, teacher, course,sc
-> where teacher.tid = course.tid
-> and sc.sid = student.sid
-> and sc.cid = course.cid
-> and teacher.tname = "张三"
-> order by score desc
-> limit 1;
33.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
mysql> select student.*, sc.score, sc.cid from student, teacher, course,sc
-> where teacher.tid = course.tid
-> and sc.sid = student.sid
-> and sc.cid = course.cid
-> and teacher.tname = "张三"
-> and sc.score = (
-> select Max(sc.score)
->from sc,student, teacher, course
-> where teacher.tid = course.tid
-> and sc.sid = student.sid
-> and sc.cid = course.cid
-> and teacher.tname = "张三"
-> );
34.统计每门课程的学生选修人数（超过 5 人的课程才统计）
mysql> select sc.cid, count(sid) as cc from sc
-> group by cid
-> having cc >5;
35.检索至少选修两门课程的学生学号
mysql> select sid, count(cid) as cc from sc
-> group by sid
-> having cc>=2;
36.按照出生日期来算，当前月日 < 出生年月的月日则，年龄减一
mysql> select student.SId as 学生编号,student.Sname as 学生姓名,
-> TIMESTAMPDIFF(YEAR,student.Sage,CURDATE()) as 学生年龄
-> from student ;
37.查询本周过生日的学生
mysql> select * from student
-> where WEEKOFYEAR(student.Sage)=WEEKOFYEAR(CURDATE());
Empty set (0.00 sec)
38.查询下周过生日的学生
mysql> select * from student
-> where WEEKOFYEAR(student.Sage)=WEEKOFYEAR(CURDATE())+1;
Empty set (0.00 sec)
39.查询本月过生日的学生
mysql> select * from student
-> where MONTH(student.Sage)=MONTH(CURDATE());
40.查询下月过生日的学生
mysql> select * from student
-> where MONTH(student.Sage)=MONTH(CURDATE())+1;
Empty set (0.00 sec)