MySQL综合练习题

题目：

请创建如下表，并创建相关约束

班级表：class				学生表：student
cid	caption	grade_id		sid	sname	gender	class_id
1	一年一班	1		1	乔丹	女	1
2	二年一班	2		2	艾弗森	女	1
3	三年二班	3		3	科比	男	2
老师表：teacher				课程表：course
tid	tname			cid	cname	teacher_id
1	张三			1	生物	1
2	李四			2	体育	1
3	王五			3	物理	2
成绩表：score					年级表：class_grade
sid	student_id	course_id	score		gid	gname
1	1	1	60		1	一年级
2	1	2	59		2	二年级
3	2	2	99		3	三年级
班级任职表：teach2cls
tcid	tid	cid
1	1	1
2	1	2
3	2	1
4	3	2
二、操作表
1、自行创建测试数据；

2、查询学生总人数；

3、查询“生物”课程和“物理”课程成绩都及格的学生id和姓名；

4、查询每个年级的班级数，取出班级数最多的前三个年级；

5、查询平均成绩最高和最低的学生的id和姓名以及平均成绩；

6、查询每个年级的学生人数；

7、查询每位学生的学号，姓名，选课数，平均成绩；

8、查询学生编号为“2”的学生的姓名、该学生成绩最高的课程名、成绩最低的课程名及分数；

9、查询姓“李”的老师的个数和所带班级数；

10、查询班级数小于5的年级id和年级名；

11、查询班级信息，包括班级id、班级名称、年级、年级级别(12为低年级，34为中年级，56为高年级)，示例结果如下；

班级id	班级名称	年级	年级级别
1	一年一班	一年级	低
12、查询学过“张三”老师2门课以上的同学的学号、姓名；

13、查询教授课程超过2门的老师的id和姓名；

14、查询学过编号“1”课程和编号“2”课程的同学的学号、姓名；

15、查询没有带过高年级的老师id和姓名；

16、查询学过“张三”老师所教的所有课的同学的学号、姓名；

17、查询带过超过2个班级的老师的id和姓名；

18、查询课程编号“2”的成绩比课程编号“1”课程低的所有同学的学号、姓名；

19、查询所带班级数最多的老师id和姓名；

20、查询有课程成绩小于60分的同学的学号、姓名；

21、查询没有学全所有课的同学的学号、姓名；

22、查询至少有一门课与学号为“1”的同学所学相同的同学的学号和姓名；

23、查询至少学过学号为“1”同学所选课程中任意一门课的其他同学学号和姓名；

24、查询和“2”号同学学习的课程完全相同的其他同学的学号和姓名；

25、删除学习“张三”老师课的score表记录；

26、向score表中插入一些记录，这些记录要求符合以下条件：①没有上过编号“2”课程的同学学号；②插入“2”号课程的平均成绩；

27、按平均成绩从低到高显示所有学生的“语文”、“数学”、“英语”三门的课程成绩，按如下形式显示： 学生ID,语文,数学,英语,有效课程数,有效平均分；

28、查询各科成绩最高和最低的分：以如下形式显示：课程ID，最高分，最低分；

29、按各科平均成绩从低到高和及格率的百分数从高到低顺序；

30、课程平均分从高到低显示（现实任课老师）；

31、查询各科成绩前三名的记录(不考虑成绩并列情况)

32、查询每门课程被选修的学生数；

33、查询选修了2门以上课程的全部学生的学号和姓名；

34、查询男生、女生的人数，按倒序排列；

35、查询姓“张”的学生名单；

36、查询同名同姓学生名单，并统计同名人数；

37、查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列；

38、查询课程名称为“数学”，且分数低于60的学生姓名和分数；

39、查询课程编号为“3”且课程成绩在80分以上的学生的学号和姓名；

40、求选修了课程的学生人数

41、查询选修“王五”老师所授课程的学生中，成绩最高和最低的学生姓名及其成绩；

42、查询各个课程及相应的选修人数；

43、查询不同课程但成绩相同的学生的学号、课程号、学生成绩；

44、查询每门课程成绩最好的前两名学生id和姓名；

45、检索至少选修两门课程的学生学号；

46、查询没有学生选修的课程的课程号和课程名；

47、查询没带过任何班级的老师id和姓名；

48、查询有两门以上课程超过80分的学生id及其平均成绩；

49、检索“3”课程分数小于60，按分数降序排列的同学学号；

50、删除编号为“2”的同学的“1”课程的成绩；

51、查询同时选修了物理课和生物课的学生id和姓名；

　　

答案：

创建表：

create table class(
cid int primary key auto_increment,
caption char(6),
grade_id int not null
);

insert class(caption,grade_id) values ('一年一班',1),('二年一班',2),('三年二班',3);

create table student(
sid int primary key auto_increment,
sname char(6) not null,
gender enum('女','男') default '男',
class_id int not null ,
foreign key(class_id) references class(cid)
on delete cascade
on update cascade
);

insert student(sname,gender,class_id) values ('乔丹','女',1),('艾弗森','女',1),('科比','男',2);


create table teacher(
tid int auto_increment,
tname char(6) not null,
primary key(tid)
);

insert teacher (tname) values ('张三'),('李四'),('王五');


create table course(
cid int primary key auto_increment,
cname char(6) not null,
teacher_id int,
foreign key(teacher_id) references teacher(tid)
on delete cascade
on update cascade
);

insert course(cname,teacher_id) values('生物',1),('体育',1),('物理',2);


create table score(
sid int auto_increment,
student_id int not null,
course_id int not null,
score int ,
primary key (sid),
foreign key (student_id) references student(sid) on delete cascade on update cascade,
foreign key (course_id) references course(cid) on delete cascade on update cascade);

insert score (student_id, course_id,score) values(1,1,60),(1,2,59),(2,2,99);


create table class_grade(
gid int auto_increment,
gname char(6) not null,
primary key (gid)
);

insert class_grade(gname) values ('一年级'),('二年级'),('三年级');


create table teach2cls(
tcid int primary key auto_increment,
tid int not null,
cid int not null,
foreign key(tid) references teacher(tid) on delete cascade on update cascade,
foreign key (cid) references class(cid) on delete cascade on update cascade);

insert teach2cls (tid,cid) values(1,1),(1,2),(2,1),(3,2);

　　

补充数据

insert class_grade(gname) values ('四年级'),('五年级'),('六年级');

insert class(caption,grade_id) values ('四年一班',4),('五年三班',5),('五年一班',5),('六年二班',6);

insert teacher (tname) values ('赵柳'),('孙策'),('狄仁杰'),("李新");

insert teach2cls (tid,cid) values(4,6),(5,5),(6,4),(6,2);

insert course(cname,teacher_id) values('语文',4),('数学',5),('英语',6),('化学',3),('美术',4);

insert student(sname,gender,class_id) values 
('alsa','女',4),('lily','女',5),('jack','男',6),('alsa','女',7),
('lucy','女',1),('bob','男',3),('乔丹','女',4),('nico','女',5),
('alex','男',3),('张良',男',4),('lily','女',2),('jack','男',7),
("kitty",'女',5),('诸葛','男',5),('妲己','女',4),('甄姬','女',6);

insert score (student_id, course_id,score) values
(4,1,58),(5,2,88),(6,3,73),(16,4,75),(16,5,92),
(7,4,65),(8,5,98),(9,6,72),(16,6,88),(17,7,63),(18,7,77),(19,7,90),
(11,3,81),(10,5,85),(12,1,63),(12,2,87),
(13,6,55),(14,3,55),(15,5,41),(6,1,80);

　　

答案：

# 2、查询学生总人数；
select 
	count(sid) 
from 	
	student;

# 3、查询“生物”课程和“物理”课程成绩都及格的学生id和姓名；
select 
	sid,sname 
from 
	student where sid in(
		select 
			student_id 
		from 
			score
		inner join 
			course 
		on 
			score.course_id = course.cid 
		where 
			cname='生物' or cname='物理' and score>=60
group by 
	score.student_id 
having 
	count(course_id)=2
	);

# 4、查询每个年级的班级数，取出班级数最多的前三个年级；
select
	grade_id,
	count(grade_id) as num
from 
	class
group by
	grade_id
order by count(grade_id) desc
limit 3;

# 5、查询平均成绩最高和最低的学生的id和姓名以及平均成绩；
select 	
	sid,
	sname,
	t1.avg_score 
from 
	student 
inner join(
	select 
		student_id,
		avg(score)as avg_score 
	from 
		score 
	group by 
		student_id 
	having 
		avg(score) in(
			(select avg(score)as low_score from score group by student_id order by avg(score) limit 1),
			(select avg(score)as high_score from score group by student_id order by avg(score) desc limit 1))
		)as t1
on 
	student.sid=t1.student_id;

# 6、查询每个年级的学生人数；
select 
	gname,
	count(sid)as student_count 
from 
	student
inner join(
	select 
		* 
	from 
		class_grade 
	inner join 
		class 
	on 
	class_grade.gid=class.grade_id
	)as t1
on 
	student.class_id=t1.cid 
group by 
	gid;

# 7、查询每位学生的学号，姓名，选课数，平均成绩；
select 
	sid, 
	sname, 
	t1.total_course, 
	t1.avg_score 
from 
	student 
left join(
	select 
		student_id,
		count(course_id)as total_course,
		avg(score)as avg_score 
	from 
		score
	group by 
		student_id
	)as t1
on 
student.sid=t1.student_id;

# 8、查询学生编号为“2”的学生的姓名、该学生成绩最高的课程名、成绩最低的课程名及分数；
select 
	sid,
	sname,
	t1.course_id,
	t1.score 
from 
	student 
inner join(
	select 
		student_id,
		course_id,
		score 
	from 
		score 
	where 
		score in(
			(select score from score where student_id=2 order by score desc limit 1),
			(select score from score where student_id=2 order by score limit 1 )
			)
		)as t1
on 
	student.sid=t1.student_id;

# 9、查询姓“李”的老师的个数和所带班级数；
select 
	total_teach,
	count(teach2cls.cid)as total_class 
from 
	teach2cls 
inner join(
	select 
		tid,
		count(tid)as total_teach 
	from 
		teacher 
	where 
		tname like "李%" 
	)as teach
on 
	teach2cls.tid=teach.tid 
group by 
	teach2cls.tid;

# 10、查询班级数小于5的年级id和年级名；
select 
	gid, gname from class_grade 
inner join(
	select 
		grade_id,
		count(cid) as class_count
	from
		class
	group by 
		grade_id
	) as t1
on 
	class_grade.gid = t1.grade_id
where 
	t1.class_count<5;

# 11、查询班级信息，包括班级id、班级名称、年级、年级级别(12为低年级，34为中年级，56为高年级)，示例结果如下；
班级id	班级名称	年级	年级级别
  1	 	一年一班	一年级	   低
  
select
	class.cid as '班级id',
	class.caption as '班级名称',
	class_grade.gname as '年级',
	case when class_grade.gid between 1 and 2 then '低'
	when class_grade.gid between 3 and 4 then '中'
	when class_grade.gid between 5 and 6 then '高' else 0 end as '年级级别'
from
	class,
	class_grade
where
	class.grade_id = class_grade.gid;


# 12、查询学过“张三”老师2门课以上的同学的学号、姓名；
select 
	sid,
	sname 
from 
	student 
where 
	sid in(
		select 
			student_id 
		from 
			score 
		inner join(
			select 
				cid 
			from 
				course 
			where 
				teacher_id =(
					select 
						tid 
					from 
						teacher 
					where 
						tname='张三'
				)
		)as t1
on 
	score.course_id=t1.cid 
group by 
	student_id 
having 
	count(course_id)=2
);

# 13、查询教授课程超过2门的老师的id和姓名；
select 
	tid, 
	tname 
from 
	teacher 
where tid in (
	select 
		teacher_id 
	from 
		course 
	group by 
		teacher_id 
	having 
		count(cid)>=2
);

# 14、查询学过编号“1”课程和编号“2”课程的同学的学号、姓名；
select 
	sid,
	sname 
from 
	student 
where 
	sid in (
		select 
			student_id 
		from 
			score 
		where 
			course_id='1' or course_id='2' 
		group by 
			student_id 
having 
	count(course_id)=2
);

# 15、查询没有带过高年级的老师id和姓名
select 
	tid,
	tname 
from 
	teacher 
where 
	tid not in(
		select 
			distinct tid 
		from 
			teach2cls 
		where 
			cid in (
				select 
					cid 
				from 
					class 
				where 
					grade_id in (
						select 
							gid 
						from 
							class_grade
						where 
							gname='五年级' or gname='六年级'
					)
			)
	);

# 16、查询学过“张三”老师所教的所有课的同学的学号、姓名；
select 
	sid, 
	sname 
from 
	student 
where sid in (
	select distinct student_id from score where course_id in (
		select cid from course where teacher_id in(
			select tid from teacher where tname='张三'
			)
		)
	);

# 17、查询带过超过2个班级的老师的id和姓名；
select 
	tid, 
	tname
from 
	teacher 
where tid in (
	select 
		tid 
	from 
		teach2cls 
	group by 
		tid 
	having 
		count(cid)>2
);

# 18、查询课程编号“2”的成绩比课程编号“1”课程低的所有同学的学号、姓名；
select
  sid,
  sname
from student
where sid in (
  select s1.student_id
  from score as s1 inner join score as s2 on s1.student_id = s2.student_id and s1.course_id = 1 and s2.course_id = 2
  where s1.score < s2.score);

# 19、查询所带班级数最多的老师id和姓名；
select 
	tid,
	tname 
from 
	teacher
where 
	tid in (
		select 
			tid 
		from 
			teach2cls 
		group by 
			tid 
		having 
			count(cid)=(
				select 
					count(cid) 
				from 
					teach2cls 
				group by 
					tid 
				order by 
					count(cid) desc 
				limit 1
			)
	);

# 20、查询有课程成绩小于60分的同学的学号、姓名；
select 
	sid,
	sname 
from 
	student 
where 
	sid in (
		select 
			student_id 
		from 
			score 
		where 
			score<60
	);

# 21、查询没有学全所有课的同学的学号、姓名；
select 
	sid,
	sname 
from 
	student 
left join (
	select 
		student_id 
	from 
		score 
	group by 
		student_id 
	having 
		count(course_id)=(
			select count(cid) from course)
	)as t1 
on 
	student.sid=t1.student_id
where 
	t1.student_id is null;

# 22、查询至少有一门课与学号为“1”的同学所学相同的同学的学号和姓名；
select 
	sid,sname 
from 
	student 
where 
	sid in (
		select 
			distinct student_id 
		from 
			score 
		where 
			course_id in( 
				select 
					course_id 
				from 
					score 
				where 
					student_id =1
			)
	) 
	and sid !=1;

# 23、查询至少学过学号为“1”同学所选课程中任意一门课的其他同学学号和姓名；
select 
	distinct sid,
	sname 
from 
	student
where 
	sid in (
		select 
			student_id 
		from 
			score 
		where 
			course_id in (
				select 
					course_id 
				from 
					score 
				where 
					student_id=1
			) 
			and student_id!=1
	);

# 24、查询和“2”号同学学习的课程完全相同的其他同学的学号和姓名；
select 
	sid,
	sname 
from 
	student 
where sid in (
	select student_id from score,
	(select course_id from score where student_id=2)as t1
	where score.course_id = t1.course_id and score.student_id !=2 group by score.student_id 
	having count(score.course_id)=(select count(course_id)from score where student_id=2)
);
	
# 25、删除学习“张三”老师课的score表记录；
delete from score where course_id in (
	select cid from course where teacher_id =(
		select tid from teacher where tname='张三')
);

# 26、向score表中插入一些记录，这些记录要求符合以下条件：①没有上过编号“2”课程的同学学号；②插入“2”号课程的平均成绩；
insert score(student_id,course_id,score)
    select t1.sid,2,t2.avg_score from(
	(select sid from student where sid not in (select student_id from score where course_id = 2)) as t1,
	(select avg(score)as avg_score from score where course_id = 2) as t2);

# 27、按平均成绩从低到高显示所有学生的“语文”、“数学”、“英语”三门的课程成绩，按如下形式显示： 学生ID,语文,数学,英语,有效课程数,有效平均分；	
select 
	student_id,
	(select score from score where course_id =(select cid from course where cname='语文') and score.student_id =s1.student_id ) as '语文',
	(select score from score where course_id =(select cid from course where cname='数学') and score.student_id =s1.student_id ) as '数学',
	(select score from score where course_id =(select cid from course where cname='英语') and score.student_id =s1.student_id ) as '英语',
	count(course_id) as '有效课程数',
	avg(score) as '有效平均分'
from 
	score as s1
group by
	student_id
order by
	avg(score);

# 28、查询各科成绩最高和最低的分：以如下形式显示：课程ID，最高分，最低分；
select 
	course_id as id,
	max(score.score) as '最高分', 
	min(score.score) as '最低分' 
from 
	course 
left join score 
on score.course_id=course.cid  
group by course_id; 

# 29、按各科平均成绩从低到高和及格率的百分数从高到低顺序；
select course_id, 
	avg(score) as avg_score,
	sum(case when score.score >= 60 then 1 else 0 end) / count(sid) * 100 as percent
from 
	score 
group by 
	course_id 
order by 
	avg(score) asc,percent desc;

# 30、课程平均分从高到低显示（现实任课老师）；
select 
	t1.cid,
	t1.tname,
	t2.avg_score 
from(
	select 
		teacher.tid as tid, 
		teacher.tname as tname,
		course.cid as cid 
	from 
		teacher 
	inner join 
		course 
	on teacher.tid = teacher_id
	)as t1
inner join
	(select course_id,avg(score)as avg_score from score group by course_id )as t2
on 
	t1.cid=t2.course_id 
order by 
	avg_score desc;

# 31、查询各科成绩前三名的记录(不考虑成绩并列情况)
select
  student_id,
  score,
  course_id
from score r1
where (SELECT count(1)
       from (select distinct
               score,
               course_id
             from score) r2
       where r2.course_id = r1.course_id AND r2.score > r1.score) <= 2
order by course_id, score DESC;


# 32、查询每门课程被选修的学生数；
select 
	course_id, 
	count(student_id) 
from 
	score 
group by 
	course_id;

# 33、查询选修了2门以上课程的全部学生的学号和姓名；
select 
	sid, 
	sname 
from 
	student 
where sid in(
	select 
		student_id 
	from 
		score 
	group by 
		student_id 
	having 
		count(course_id)>2);

# 34、查询男生、女生的人数，按倒序排列；
select 
	gender, 
	count(sid) 
from 
	student 
group by 
	gender 
order by 	
	count(sid) desc;

# 35、查询姓“张”的学生名单；
select 
	* 
from 
	student 
where 
	sname like "张%";

# 36、查询同名同姓学生名单，并统计同名人数；
select 
	sname,
	count(sid) 
from 
	student 
group by 
	sname 
having 
	count(sid)>1;

# 37、查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列；
select 
	course_id, 
	avg(score) 
from 
	score 
group by 
	course_id 
order by 
	avg(score),
	course_id desc;

# 38、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, 
	t1.score 
from 
	student 
inner join  (
	select 
		student_id, 
		score 
	from 
		score 
	where score.score<60 and course_id in (
		select 
			cid 
		from 
			course 
		where cname='数学'
	) 
)as t1
on 	
	t1.student_id=student.sid;

# 39、查询课程编号为“3”且课程成绩在80分以上的学生的学号和姓名；
select 
	sid,
	sname 
from 
	student 
where sid in(
	select 
		student_id 
	from 
		score 
	where 
	course_id=3 and score>80
);

# 40、求选修了课程的学生人数
select 
	coalesce(student_id,"总人数")as id,
	count(course_id) 
from 
	score 
group by 
	student_id 
with rollup;

# 41、查询选修“王五”老师所授课程的学生中，成绩最高和最低的学生姓名及其成绩；
select 
	s1.student_id,
	low_score,
	s2.student_id,
	high_score 
from(
	select 
		tid,
		student_id,
		score as low_score 
	from 
		(select student_id,cid,cname,score,tid 
		from score 
		inner join
			(select tid,tname,cid,cname from teacher inner join course on teacher.tid=course.teacher_id where tname='王五')as t1
		on score.course_id=t1.cid)as t2 order by score limit 1) as s1
	inner join (
		select tid,student_id,score as high_score from 
			(select student_id,cid,cname,score,tid 
			from score 
			inner join
				(select tid,tname,cid,cname from teacher 
				inner join 
					course 
				on teacher.tid=course.teacher_id where tname='王五')as t1
			on score.course_id=t1.cid)as t2 order by score desc limit 1) as s2
	on s1.tid=s2.tid;


# 42、查询各个课程及相应的选修人数；
select 
	course_id ,
	count(student_id) 
from 
	score 
group by 
	course_id;

# 43、查询不同课程但成绩相同的学生的学号、课程号、学生成绩；
select distinct
	s1.course_id,
	s1.student_id,
	s1.score,
	s2.course_id,
	s2.student_id,
	s2.score 
from 
	score as s1, 
	score as s2 
where 
s1.score = s2.score and s1.course_id != s2.course_id;


# 44、查询每门课程成绩最好的前两名学生id和姓名；
select student.sid,student.sname,course.cname, score.score
	from score
inner join (
	select course_id, score, ranking
		from (
			 select a.course_id, a.score, count(1) as ranking
				from 
					(select course_id, score from score group by course_id, score order by course_id, score desc)as a
				inner join 
					(select course_id, score from score group by course_id, score order by course_id, score desc)as b
				on a.course_id = b.course_id and a.score <= b.score group by course_id, score
		) as t1
		where ranking in (1, 2) order by course_id, ranking)as s1
on score.course_id = s1.course_id and score.score = s1.score
inner join student
	on score.student_id = student.sid
inner join course 
	on score.course_id = course.cid;


# 45、检索至少选修两门课程的学生学号；
select 
	student_id 
from 
	score 
group by 
	student_id 
having 
	count(course_id)>=2;

# 46、查询没有学生选修的课程的课程号和课程名；
select 
	course.cid,
	course.cname 
from 
	course 
left join 
	score 
on 
	course.cid=score.course_id 
where 
	score.student_id is null;

# 47、查询没带过任何班级的老师id和姓名；
select 
	teacher.tid,
	tname 
from 
	teacher 
left join 
	teach2cls 
on 
	teacher.tid=teach2cls.tid 
where 
	teach2cls.tcid is null;

# 48、查询有两门以上课程超过80分的学生id及其平均成绩；
select 
	student_id,
	avg(score) 
from 
	score 
where 
	score>80 
group by 
	student_id 
having 
	count(course_id)>2;

# 49、检索“3”课程分数小于60，按分数降序排列的同学学号；
select 
	student_id,
	score 
from 
	score 
where 
	score<60 and course_id=3 
order by 
	score desc;

# 50、删除编号为“2”的同学的“1”课程的成绩；
delete from score where student_id='2' and course_id='1';

# 51、查询同时选修了物理课和生物课的学生id和姓名；
select 
	student.sid,
	student.sname 
from 
	student 
where sid in (
        select 
			student_id 
		from 
			score 
		where 
			course_id IN (
                select 
					cid 
				from 
					course 
				where cname = '物理' or cname = '生物'
			)
        group by 
			student_id 
		having 
			count(course_id) = 2
    );