sql综合练习题

一、表关系
年级表：class_grade
create table class_grade(
    gid int primary key auto_increment,
    gname varchar(20) not null
    );
insert into class_grade(gname) values
    (‘一年级‘),
    (‘二年级‘),
    (‘三年级‘);
班级表：class
create table class(
    cid int primary key auto_increment,
    caption varchar(30) not null,
    grade_id int not null,
    constraint class_name foreign key(grade_id)
    references class_grade(gid)
    on delete cascade
    on update cascade
    );
insert into class(caption,grade_id) values
    (‘一年一班‘,1),
    (‘二年一班‘,2),
    (‘三年二班‘,3);
    
学生表：student
create table student(
    sid int primary key auto_increment,
    sname varchar(20) not null,
    gender enum(‘女‘,‘男‘),
    class_id int not null,
    constraint student_name foreign key(class_id)
    references class(cid)
    on delete cascade
    on update cascade
    );
insert into student(sname,gender,class_id) values
    (‘乔丹‘,‘女‘,1),
    (‘艾弗森‘,‘女‘,1),
    (‘科比‘,‘女‘,2);
    
老师表：teacher
create table teacher(
    tid int primary key auto_increment,
    tname varchar(30) not null
    );
insert into teacher(tname) values
    (‘张三‘),
    (‘李四‘),
    (‘王五‘);
    
课程表：course
create table course(
    cid int primary key auto_increment,
    cname varchar(30) not null,
    teacher_id int not null,
    constraint teacher_name foreign key(teacher_id)
    references teacher(tid)
    on delete cascade
    on update cascade
);
insert into course(cname,teacher_id) values
    (‘生物‘,1),
    (‘体育‘,1),
    (‘物理‘,2);
    
成绩表：score
create table score(
    sid int primary key auto_increment,
    student_id int not null,
    course_id int not null,
    score int not null,
    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 into score(student_id,course_id,score) values
    (1,1,60),
    (1,2,59),
    (2,2,99);
    
班级任职表：teach2cls
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 into teach2cls(tid,cid) values
    (1,1),
    (1,2),
    (2,1),
    (3,2);
    
2、查询学生总人数
select count(sname) 总人数 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
inner join
    (
        select 
            student_id
        from 
            score
        where
            course_id in (
                select
                    cid
                from
                    course
                where
                    cname in (‘生物‘,‘物理‘)
            ) and  score >= 60
    ) as t1 on t1.student_id = student.sid;
    
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
    class_grade.gid,
    class_grade.gname
from
    class_grade
inner join
(
    select 
        grade_id,
        count(cid)
    from
        class
    group by 
        grade_id
    order by 
        grade_id desc
    limit 3
) as t1 on t1.grade_id = class_grade.gid;
    
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
    student.sid,
    student.sname,
    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 max_score
            from
                score
            group by 
                student_id
            order by
                avg(score) desc
            limit 1
            ),
            (
            select
                avg(score) as min_score
            from
                score
            group by
                student_id
            order by
                avg(score)
            limit 1
            )
        )
    ) as t1 on t1.student_id = student.sid;

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

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

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
    student.sname,
    student.sid,
    t1.score
from
(
    select
        student_id,
        course_id,
        score
    from 
        score
    where student_id = 2 and score in
    (
        (
        select
            max(score)
        from
            score
        where student_id = 2),
        (
        select 
            min(score)
        from
            score
        where student_id =2)
    ) 
)as t1
inner join student on t1.student_id = student.sid
inner join course on t1.course_id = course.cid;

9、查询‘李’的老师的个数和所带班级数;
select
    count(teacher.tname) as ‘李%个数‘,
    count(teach2cls.cid) as ‘班级数量‘
from teacher left join teach2cls on teach2cls.tid = teacher.tid
where teacher.tname like ‘李%‘;

10、查询班级数小于5年级的id和年级名;
select
    gid,
    gname,
    count(cid)
from
    class_grade
inner join class on gid = grade_id
group by
    gid
having
    count(cid) < 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）
select
    class.cid as ‘班级id‘,
    class.caption as ‘班级名称‘,
    class_grade.gid 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
left join class_grade on class_grade.gid=class.grade_id;

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
left join course on course_id = course.cid
where course.teacher_id in 
    (    
        select 
            tid
        from 
            teacher
        where tname = ‘张三‘
    )
group by
    student_id
having count(course.cid)>=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
inner join 
    (
    select
        teacher_id,
        count(cid)
    from
        course
    group by
        teacher_id
    having count(cid) >=2
) as t1 on t1.teacher_id = teacher.tid;

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 
    course_id
from
    score
group by
    course_id
having
    course_id in (1,2)
)

15、查询没有带过高年级的老师id和姓名;
select
    tid,
    tname
from
    teacher
where tid  in
(
select 
    tid
from
    teach2cls
where tid in 
(select
    cid
from
    class
where grade_id in (5,6)));

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
        student_id
    from
        score
    where course_id in 
        (    
        select
            cid
        from
            course
        inner join teacher on teacher_id = teacher.tid
        where teacher.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’1‘课程低的所有同学的学号、姓名
select 
    sid,
    sname
from
    student
where sid in (
select 
    t1.student_id
from
(
    select
        student_id,
        score
    from
        score
    where 
        course_id =2
) as t1
inner join
(
    select
        student_id,
        score
    from
        score
    where 
        course_id =1
) as t2 on t1.student_id = t2.student_id
where t1.score < t2.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 =
(select
    tid
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
where sid not in (
select
    student_id
from
    score
group by
    student_id
having
    count(course_id) = (select count(cid) from course));
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
    student_id
from
    score
where course_id in 
(select
    course_id
from
    score
where student_id = 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
    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)
having
    student_id !=1
);

24、查询和‘2’号同学学习的课程完全相同的其它同学的学号和姓名
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 course.teacher_id = (
select 
    tid
from 
    teacher
where teacher.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 into score(student_id,course_id,score) 
     select t1.sid,2,t2.avg 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 from score group by course_id having 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 sc.student_id as  学生ID,
        (select score.score from score left join course on score.course_id = course.cid 
          where course.cname = ‘生物‘ and score.student_id = sc.student_id) as 生物,
        (select score.score from score left join course on score.course_id = course.cid 
          where course.cname = ‘体育‘ and score.student_id = sc.student_id) as 体育,
        (select score.score from score left join course on score.course_id = course.cid 
          where course.cname = ‘物理‘ and score.student_id = sc.student_id) as 物理,
        count(sc.course_id) as ‘有效课程数‘,avg(sc.score) as ‘有效平均分‘
    from score as sc group by sc.student_id order by avg(sc.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，高低分;
    select course_id as "课程ID",max(score) as "最高分",min(score) as "最低分" from score
    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 as ‘课程ID‘,AVG(score) as ‘平均成绩‘,
    sum(CASE WHEN score > 60 then 1 ELSE 0 END)/COUNT(1)*100 as ‘及格率‘
    from score
    GROUP BY course_id ORDER BY ‘平均成绩‘ ASC,‘及格率‘ desc;

30、课程平均分从高到低显示（现实任课老师）；
SELECT score.course_id as ‘课程ID‘,avg(score) as ‘平均分‘ from score
inner join course on score.course_id = course.cid
GROUP BY 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 score.sid,score.course_id,score.score,t1.first_score,t1.sencond_score,t1.third_score from score LEFT JOIN
(SELECT sid,
    (select  score from score as s2 where s2.course_id=s1.course_id ORDER BY score desc LIMIT 0,1) as first_score,
    (select  score from score as s2 where s2.course_id=s1.course_id ORDER BY score desc LIMIT 1,1) as sencond_score,
    (select  score from score as s2 where s2.course_id=s1.course_id ORDER BY score desc LIMIT 2,1) as third_score
from score as s1)as t1 on score.sid = t1.sid
WHERE score.score in (t1.first_score,t1.sencond_score,t1.third_score)

32、查询每门课程被选修的学生数；
SELECT score.course_id as ‘课程ID‘,count(student_id) as ‘学生数‘ 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 student.sid,student.sname from student WHERE sid in (
SELECT score.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) as sum from student
group by gender
order by sum desc

35、查询姓“张”的学生名单；
SELECT sname 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 as ‘名字‘,count(sname) as ‘同名人数‘ from student
GROUP BY sname
HAVING count(sname) >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 score.course_id,avg(score) as avg from score
INNER JOIN course on course.cid = course_id
GROUP BY course_id
ORDER BY avg ASC,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 sid,sname from student
where sid in (
SELECT score.student_id  from score
INNER JOIN course on course.cid = score.course_id
WHERE course.cname = ‘体育‘ and score.score <60);

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 score.student_id  from score
INNER JOIN course on course.cid = course_id
WHERE course_id = 3 and score.score > 80);

40、求选修了课程的学生人数
select course_id as ‘课程ID‘,count(student_id) as ‘学生人数‘ from score group by course_id;

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 student.sname,max(score),min(score) from score
INNER JOIN student on score.student_id = student.sid
WHERE course_id in (
SELECT cid from course
WHERE teacher_id in (
SELECT tid FROM teacher
WHERE tname = ‘王五‘))
GROUP BY student_id
ORDER BY max(score) DESC,MIN(score) ASC
LIMIT 2

42、查询各个课程及相应的选修人数；
SELECT score.course_id as ‘ID‘,course.cname as ‘课程‘,count(student_id) as ‘人数‘ from score
LEFT JOIN course on score.course_id = course.cid
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,s2.course_id,s1.score,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 score.sid,score.course_id,score.score,t1.first_score,t1.sencond_score from score LEFT JOIN
(SELECT sid,
    (select  score from score as s2 where s2.course_id=s1.course_id ORDER BY score desc LIMIT 0,1) as first_score,
    (select  score from score as s2 where s2.course_id=s1.course_id ORDER BY score desc LIMIT 1,1) as sencond_score
from score as s1)as t1 on score.sid = t1.sid
WHERE score.score <= t1.first_score and score.score >= t1.sencond_score

45、检索至少选修两门课程的学生学号；
SELECT score.student_id as ‘学生ID‘,count(course_id) as ‘课程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 cid,cname from course
WHERE cid not IN(
SELECT score.course_id from score
GROUP BY score.course_id)

47、查询没带过任何班级的老师id和姓名；
SELECT tid,tname from teacher
WHERE tid not in(
SELECT teach2cls.cid from teach2cls
GROUP BY teach2cls.cid)

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 score.student_id as ‘学生ID‘,avg(score) as ‘平均成绩‘ from score
WHERE score > 30 
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 score.student_id 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 score.student_id = 2 and score.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 sid,sname from student
WHERE sid in(
SELECT score.student_id from score
WHERE course_id in (
SELECT cid from course
WHERE course.cname in (‘生物‘,‘物理‘))
GROUP BY student_id
HAVING count(course_id) =2)