MySQL练习50道

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MySQL练习

50道经典SQL练习题

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

建表语句

学⽣表 Student

create table Student(
    SId varchar(10),
    Sname varchar(10),
    Sage datetime,
    Ssex varchar(10)
);

课程表 Course

create table Course(
    CId varchar(10),
    Cname nvarchar(10),
    TId varchar(10)
);

教师表 Teacher

create table Teacher(
    TId varchar(10),
    Tname varchar(10)
);

成绩表 SC

create table SC(
    SId varchar(10),
    CId varchar(10),
    score decimal(18,1)
);

插入数据

学⽣表 Student

-- 学生表 Student
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' , '孙⻛' , '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');

课程表 Course

-- 科⽬表 Course 
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

-- 教师表 Teacher 
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

-- 成绩表 SC 
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

SELECT 
    tt1.SId
    ,t3.Sname
    ,tt1.语文
    ,tt1.数学
FROM(
    SELECT 
    t1.SId
    ,t1.score '语文'
    ,t2.score '数学' 
    FROM (
        ( SELECT SId, score FROM SC WHERE CId = '01' ) t1
    LEFT JOIN 
        ( SELECT SId, score FROM SC WHERE CId = '02' ) t2 
    ON t1.SId = t2.SId
    ) WHERE t1.score>t2.score )tt1
LEFT JOIN Student t3
on t3.SId=tt1.SId

2.查询同时存在" 01 “课程和” 02 "课程的情况

select  t1.SId
        ,t1.CId t1_CId
        ,t2.CId t2_CId
from(
    select  SId
            ,CId
    from SC 
    where CId='01'
    ) t1
    join
    (
        select  SId
                ,CId
        from SC 
        where CId='02'
    )t2
    on t2.SId=t1.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 )

select  t1.SId
        ,t1.CId t1_CId
        ,t2.CId t2_CId
from(
    select  SId
            ,CId
    from SC 
    where CId='01'
    ) t1
    left join
    (
        select  SId
                ,CId
        from SC 
        where CId='02'
    )t2
    on t2.SId=t1.SId

4.查询可能不存在" 01 “课程但存在” 02 "课程的情况

select  t2.SId
        ,t1.CId t1_CId
        ,t2.CId t2_CId
from(
    select  SId
            ,CId
    from SC 
    where CId='01'
    ) t1
    right join
    (
        select  SId
                ,CId
        from SC 
        where CId='02'
    )t2
    on t2.SId=t1.SId

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

select  t1.SId
        ,t2.Sname
        ,round(t1.avg_score,2)
from(
    select  SId
        ,avg(score) avg_score
    from SC 
    group by SId
    having avg_score>=60
) t1  join Student t2
on t1.SId=t2.SId;

6.查询在 SC 表存在成绩的学⽣信息

select  t1.SId
        ,t2.Sname
        ,t2.Sage
        ,t2.Ssex
from (
    select distinct SId
    from SC 
    where score is not null
) t1 join Student t2
on t1.SId=t2.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 )

select  t2.SId
        ,t2.Sname
        ,t1.count_CId
        ,t1.sum_score
from(
    select  SId
        ,count(CId) count_CId
        ,sum(score) sum_score
    from SC 
    group by SId
) t1 right join Student t2
on t1.SId=t2.SId=

8.查询「李」姓⽼师的数量

select count(Tname)
from Teacher
where Tname like '李%';

9.查询学过「张三」⽼师授课的同学的信息

#-------------------方式一-------------------------
select  ttt2.SId
        ,ttt2.Sname
from(
    select tt2.SId SId
    from(
        select  t2.CId t2_CId
                ,t2.Cname t2_Cname
        from(
            select TId
            from Teacher
            where Tname='张三'
        ) t1 left join Course t2
        on t1.TId=t2.TId
    ) tt1 left join SC tt2
    on tt1.t2_CId=tt2.CId
)ttt1 left join Student ttt2
on ttt1.SId=ttt2.SId

#-------------------方式二-------------------------
select  t1.SId
        ,t2.Sname
from(
    select  SId
    from SC
    where CId=(
        select CId
        from Course 
        where TId=(
            select TId
            from Teacher
            where Tname='张三'
        )
    )
)t1 left join Student t2
on t1.SId=t2.SId

10.查询没有学全所有课程的同学的信息

select  t2.SId
				,t2.Sname
				,if(t1.num2 is null,0,t1.num2) num3
		from(
				select  SId
								,count(CId) num2
				from SC
				group by SId
		)t1 right join Student t2
		on t1.SId=t2.SId
		having num3<(select count(CId)  from Course)

11.查询⾄少有⼀⻔课与学号为" 01 "的同学所学相同的同学的信息

select  t2.SId
        ,t2.Sname
        ,t1.CId
from SC 
t1 join Student t2
on t1.SId=t2.SId
having t2.SId!='01' and t1.CId in (
    select  CId from SC where SId='01')

12.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  tt1.SId
        ,tt1.Sname
        ,count(tt1.CId) num
from(
    select  t2.SId SId 
        ,t2.Sname Sname
        ,t1.CId CId
    from SC t1
    join Student t2
    on t1.SId=t2.SId
    having t2.SId!='01' and
    t1.CId in (select CId
                from SC 
                where SId='01')
)tt1 group by tt1.SId,tt1.Sname
having num=(select count(SId) from SC where SId='01')

13.查询没学过"张三"⽼师讲授的任⼀⻔课程的学⽣姓名

select  SId
        ,Sname
from Student
where SId not in (
    select SId
    from SC 
    where CId in (
        select  CId
        from Course where TId=(
            select TId
            from Teacher
            where Tname='张三'
        )
    )
);

14.查询两⻔及其以上不及格课程的同学的学号，姓名及其平均成绩

select  t1.SId
        ,t2.Sname
        ,t1.avg_score
from(
    select  SId
            ,count(score) count_score
            ,round(avg(score),2) avg_score
    from SC
    where score < 60
    group by SId
    having count_score>=2
) t1  left join Student t2
on t1.SId=t2.SId

15.检索" 01 "课程分数⼩于 60，按分数降序排列的学⽣信息

select  SId
        ,Sname
from Student 
where SId in(
        select SId
        from SC 
        where CId='01' and score < 60
        order by 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

select  t1.SId
        ,t2.chinese
        ,t3.math
        ,t4.english
        ,t1.avg_score
from(
    select  SId
            ,round(avg(score),2) avg_score
    from SC
    group by SId
) t1  left join 
(select  SId,score chinese from SC where CId='01') t2
on t1.SId=t2.SId
 left join
(select  SId,score math from SC where CId='02') t3
on t1.SId=t3.SId
 left join 
(select  SId,score english from SC where CId='03') t4
on t1.SId=t4.SId
order by t1.avg_score 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

select  t1.CId
        ,t2.Cname
        ,t1.count_CId
        ,t1.max_score
        ,t1.min_score
        ,t1.avg_score
        ,t1.及格率 及格率
        ,t1.中等率 中等率
        ,t1.优良率 优良率
        ,t1.优秀率 优秀率
from(
    select  CId
            ,count(CId) count_CId
            ,max(score) max_score
            ,min(score) min_score
            ,avg(score) avg_score
            ,round(sum(if(score>=60,1,0))*100 /count(score),2) '及格率'
			,round(sum(if(score>=70 and score<=80,1,0))*100 /count(score),2) '中等率'
            ,round(sum(if(score>=80 and score<=90,1,0))*100 /count(score),2) '优良率'
            ,round(sum(if(score>=90,1,0))*100 /count(score),2) '优秀率'
    from SC 
    group by CId
) t1 join Course t2
on t1.CId=t2.CId
order by t1.count_CId desc,t1.CId

18.按各科平均成绩进⾏排序，并显示排名， Score 重复时保留名次空缺

set @i :=0;
set @j :=0;
set @k :=0;
select  t1.CId
        ,t1.score
				,@j :=t1.score
				,if(@k=@j,@i,@i :=@i+1) rank
        ,@k :=@j
from(
    select  CId
        ,score
    from SC 
    order by score desc
) t1

19.按各科平均成绩进⾏排序，并显示排名， Score 重复时不保留名次空缺

set @i :=0;
select  t1.CId
        ,t1.avg_score
        ,@i :=@i+1
from(
    select  CId
        ,avg(score) avg_score
    from SC 
    group by CId
    order by avg_score desc
) t1

20.查询学⽣的总成绩，并进⾏排名，总分重复时保留名次空缺

1 2 2 4 5 6

set @i :=0;
set @j :=0;
set @k :=0;
set @n :=0;
select t1.SId
        ,t1.sum_score
				,@n :=@n+1
        ,@j :=t1.sum_score
        ,if(@k=@j,@i,@i :=@n) rank
        ,@k :=@j
from(
    select  SId
            ,sum(score) sum_score
    from SC 
    group by SId
    order by sum_score desc
) t1

21.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

1 2 2 2 3 4 5

set @i :=0;
set @j :=0;
set @k :=0;
select t1.SId
        ,t1.sum_score
        ,@j :=t1.sum_score
        ,if(@k=@j,@i,@i :=@i+1) rank
        ,@k :=@j
from(
    select  SId
            ,sum(score) sum_score
    from SC 
    group by SId
    order by sum_score desc
) t1

22.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  t2.CId
        ,t2.Cname
        ,t1.sum1 '[100-85)'
        ,t1.sum2 '[85-70)'
        ,t1.sum3 '[70-60)'
        ,t1.sum4 '[60-0)'
from(
    select  CId
            ,concat(round(sum(if(score>85 and score<=100,1,0))*100/count(score),2),'%') sum1
            ,concat(round(sum(if(score>70 and score<=85,1,0))*100/count(score),2) ,'%')sum2
            ,concat(round(sum(if(score>60 and score<=70,1,0))*100/count(score),2) ,'%')sum3
            ,concat(round(sum(if(score>0 and score<=60,1,0))*100/count(score),2) ,'%')sum4
    from SC 
    group by CId
) t1 join Course t2
on t1.CId=t2.CId

23.查询各科成绩前三名的记录

 SET @i := 0;
 SET @p := 0;
 SET @q := 0;
select  t1.SId
        ,t2.Sname
        ,t1.CId
        ,t1.score
        ,t1.rn
from (
    select  SId
            ,CId
            ,@p :=CId
            ,if(@p=@q,@i :=@i+1,@i :=1) rn
            ,@q :=@p
            ,score
    from SC
    order by CId, score desc
) t1 join Student t2
on t1.rn<=3 and t1.SId=t2.SId
order by t1.CId,t1.rn

24.查询每⻔课程被选修的学⽣数

select  t1.CId
        ,t2.Cname
        ,t1.amount
from(
    select  CId
        ,count(SId) amount
    from SC 
    group by CId
) t1 join Course t2
on t1.CId=t2.CId

25.查询出只选修两⻔课程的学⽣学号和姓名

select  t1.SId
        ,t2.Sname
from(
    select  SId
        ,count(CId) amount
    from SC 
    group by SId
    having amount=2
) t1 join Student t2
on t1.SId=t2.SId

26.查询男⽣、⼥⽣⼈数

select  Ssex
        ,count(Ssex)
from Student
group by Ssex

27.查询名字中含有「⻛」字的学⽣信息

select *
from Student
where Sname like '%风%'

28.查询同名同性学⽣名单，并统计同名⼈数

select  Sname
				,Ssex
        ,count(Sname) amount
from Student
group by Sname,Ssex
having amount>1

29.查询 1990 年出⽣的学⽣名单

select Sname
			 ,Sage
from Student
where Sage>='1990-01-01' and Sage<='1990-12-31';

30.查询每⻔课程的平均成绩，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  t1.CId
        ,t2.Cname
        ,t1.avg_score
from(
    select  CId
        ,avg(score) avg_score
    from SC
    group by CId
) t1 join Course t2
on t1.CId=t2.CId
order by t1.avg_score desc,t1.CId asc

31.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  t1.SId
        ,t2.Sname
        ,t1.avg_score
from(
    select  SId
            ,avg(score) avg_score
    from SC 
    group by SId
    having avg_score>=85
) t1 join Student t2
on t1.SId=t2.SId

32.查询课程名称为「数学」，且分数低于 60 的学⽣姓名和分数

select  t1.SId
        ,t2.Sname
        ,t1.score
from(
    select  SId
            ,score
    from SC 
    where CId=(
        select  CId
        from Course
        where Cname='数学'
    ) and score<60
) t1 join Student t2
on t1.SId=t2.SId

33.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）

#----------------------方式一——————————————————————————————————
select  t3.SId
        ,t3.Sname
        ,t2.Cname
        ,t1.score
from(
    select  SId
            ,CId
            ,score
    from SC 
) t1 join Course t2
on t1.CId=t2.CId
right join Student t3
on t1.SId=t3.SId
#----------------------方式二——————————————————————————————————
select  t2.SId
        ,t1.chinese
        ,t1.math
        ,t1.english
from(
    select  SId
            ,sum(case CId when '01' then score else 0 end) as chinese
            ,sum(case CId when '02' then score else 0 end) as math
            ,sum(case CId when '03' then score else 0 end) as english
    from SC
    group by SId
) t1 right join Student t2
on t1.SId=t2.SId

34.查询任何⼀⻔课程成绩在 70 分以上的姓名、课程名称和分数

select  t1.SId
        ,t2.Sname
        ,t3.Cname
        ,t1.score
from(
        select  SId
            ,CId
            ,score
    from SC 
    where score>70
) t1 join Student t2
on t1.SId=t2.SId
join Course t3
on t1.CId=t3.CId

35.查询不及格的课程

select  t2.Cname
from(
    select distinct CId
    from SC 
    where score<60
) t1 join Course t2
on t1.CId=t2.CId

#-------------------------------------------
select   t3.Sname
        ,t2.Cname
from(
    select  CId
            ,SId
    from SC 
    where score<60
) t1 join Course t2
on t1.CId=t2.CId
join Student t3
on t1.SId=t3.SId

36.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  SId
        ,Sname
from Student
where SId in (
    select  SId
    from SC 
    where CId='01' and score >=80
)

37.求每⻔课程的学⽣⼈数

select  t1.CId
        ,t2.Cname
        ,t1.amount
from (
    select  CId
            ,count(SId) amount
    from SC 
    group by CId
) t1 join Course t2
on t1.CId=t2.CId

38.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  t1.SId
        ,t2.Sname
        ,t1.CId
				,t1.score
from (
      select  SId
							,CId
							,score
			from SC 
			where score = (
						select  max(score) max_score
					from SC 
					where CId in(
							select  CId
							from Course
							where TId=(
									select  TId
									from Teacher
									where Tname='张三'
							)
					)
)
) t1 join Student t2
on t1.SId=t2.SId
#-------------------------------------------------------
select  t1.SId
        ,t2.Sname
        ,t1.CId
		,t1.score
from (
    select  SId
            ,CId
            ,score
    from SC 
    where CId=(
            select  CId
            from Course
            where TId=(
                    select  TId
                    from Teacher
                    where Tname='张三'
            )
    )
)t1 join Student t2
on t1.SId=t2.SId
order by t1.score desc
limit 1;
#---------------------假设张三老师带两门课-----------------------
select  tt1.SId
        ,tt2.Sname
        ,tt1.CId
        ,tt1.max_score
from(
        select  t2.SId SId
                ,t1.CId CId
                ,t1.max_score max_score
        from(
            select  CId
                    ,max(score) max_score
            from SC 
            where CId in(
                    select  CId
                    from Course
                    where TId=(
                            select  TId
                            from Teacher
                            where Tname='张三'
                    )
            )
            group by CId
        ) t1 join SC t2
        on t1.CId=t2.CId
        and t1.max_score=t2.score
)tt1 join Student tt2
on tt1.SId=tt2.SId

39.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  tt1.SId
        ,tt2.Sname
        ,tt1.CId
        ,tt1.max_score
from(
        select  t2.SId SId
                ,t1.CId CId
                ,t1.max_score max_score
        from(
            select  CId
                    ,max(score) max_score
            from SC 
            where CId in(
                    select  CId
                    from Course
                    where TId=(
                            select  TId
                            from Teacher
                            where Tname='张三'
                    )
            )
            group by CId
        ) t1 join SC t2
        on t1.CId=t2.CId
        and t1.max_score=t2.score
)tt1 join Student tt2
on tt1.SId=tt2.SId

40.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  distinct 
				t1.SId
				,t3.Sname
				,t1.CId
				,t1.score
from SC t1
join SC t2
on t1.score=t2.score and t1.CId!=t2.CId
join Student t3
on t1.SId=t3.SId

41.查询每⻔课程成绩最好的前两名

(select  SId
        ,CId
        ,score 
from SC 
where CId='01' 
order by score desc 
limit 2)
union all
(select  SId
        ,CId
        ,score
from SC 
where CId='02' 
order by score desc
limit 2)
union all
(select  SId
        ,CId
        ,score
from SC 
where CId='03' 
order by score desc
limit 2)
#------------------------加上学生姓名------------------------
(select  t1.SId
        ,t2.Sname
        ,t1.CId
        ,t1.score
from(
    select  SId
            ,CId
            ,score 
    from SC 
    where CId='01' 
    order by score desc 
    limit 2
) t1  join Student t2
on t1.SId=t2.SId)
union 
    (select  t3.SId
            ,t4.Sname
            ,t3.CId
            ,t3.score
    from(
        select  SId
                ,CId
                ,score 
        from SC 
        where CId='02' 
        order by score desc 
        limit 2
) t3  join Student t4
on t3.SId=t4.SId)
union
    (select  t5.SId
            ,t6.Sname
            ,t5.CId
            ,t5.score
    from(
        select  SId
                ,CId
                ,score 
        from SC 
        where CId='03' 
        order by score desc 
        limit 2
) t5  left join Student t6
on t5.SId=t6.SId)

42.统计每⻔课程的学⽣选修⼈数（超过 5 ⼈的课程才统计）。

select  t1.CId
        ,t2.Cname
        ,t1.amount
from(
    select  CId
            ,count(SId) amount
    from SC 
    group by CId
    having amount>5
) t1 join Course t2
on t1.CId=t2.CId

43.检索⾄少选修两⻔课程的学⽣学号

 select  SId
         ,count(CId) amount
    from SC 
    group by SId
    having amount>=2
 #-------------------加上学生姓名------------------
 select  t1.SId
        ,t2.Sname
        ,t1.amount
from(
    select  SId
            ,count(CId) amount
    from SC 
    group by SId
    having amount>=2
) t1 join Student t2
on t1.SId=t2.SId

44.查询选修了全部课程的学⽣信息

select  t1.SId
        ,t2.Sname
        ,t1.amount
from(
    select  SId
            ,count(CId) amount
    from SC 
    group by SId
    having  amount =(
        select  count(CId)
        from  Course
    )
) t1 join Student t2
on t1.SId=t2.SId

45.查询各学⽣的年龄，只按年份来算

select  SId
        ,Sname
        ,year(now()) - date_format(Sage,'%Y')  age
from Student

46.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
        ,if(date_format(now(),'%m-%d') < date_format(Sage,'%m-%d'),
        year(now()) - date_format(Sage,'%Y')-1,
        year(now()) - date_format(Sage,'%Y')) age
from Student

47.查询本周过⽣⽇的学⽣

select  *
from Student
where week(now())=week(Sage)

48.查询下周过⽣⽇的学⽣

select  *
from Student
where week(now())+1=week(Sage)
#---------------------------------------------------------
SELECT	SId
        ,SName
        ,Sage
        ,week(Sage)
from Student
where week(Sage) = week(date_add(now(),INTERVAL 1 Week))

49.查询本⽉过⽣⽇的学⽣

select  *
from Student
where month(now())=month(Sage)

50.查询下⽉过⽣⽇的学⽣

select  *
from Student
where month(now())+1=month(Sage)
#----------------------------------------------------------
SELECT	SId
        ,SName
        ,Sage
        ,month(Sage)
from Student
where month(Sage) = month(date_add(now(),INTERVAL 1 Month))

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MySQL练习50道

MySQL练习

数据表介绍

建表语句

插入数据

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

2.查询同时存在" 01 “课程和” 02 "课程的情况

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 )

4.查询可能不存在" 01 “课程但存在” 02 "课程的情况

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

6.查询在 SC 表存在成绩的学⽣信息

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 )

8.查询「李」姓⽼师的数量

9.查询学过「张三」⽼师授课的同学的信息

10.查询没有学全所有课程的同学的信息

11.查询⾄少有⼀⻔课与学号为" 01 "的同学所学相同的同学的信息

12.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

13.查询没学过"张三"⽼师讲授的任⼀⻔课程的学⽣姓名

14.查询两⻔及其以上不及格课程的同学的学号，姓名及其平均成绩

15.检索" 01 "课程分数⼩于 60，按分数降序排列的学⽣信息

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

18.按各科平均成绩进⾏排序，并显示排名， Score 重复时保留名次空缺

19.按各科平均成绩进⾏排序，并显示排名， Score 重复时不保留名次空缺

20.查询学⽣的总成绩，并进⾏排名，总分重复时保留名次空缺

21.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

22.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

23.查询各科成绩前三名的记录

24.查询每⻔课程被选修的学⽣数

25.查询出只选修两⻔课程的学⽣学号和姓名

26.查询男⽣、⼥⽣⼈数

27.查询名字中含有「⻛」字的学⽣信息

28.查询同名同性学⽣名单，并统计同名⼈数

29.查询 1990 年出⽣的学⽣名单

30.查询每⻔课程的平均成绩，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

31.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

32.查询课程名称为「数学」，且分数低于 60 的学⽣姓名和分数

33.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）

34.查询任何⼀⻔课程成绩在 70 分以上的姓名、课程名称和分数

35.查询不及格的课程

36.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

37.求每⻔课程的学⽣⼈数

38.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

39.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

40.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

41.查询每⻔课程成绩最好的前两名

42.统计每⻔课程的学⽣选修⼈数（超过 5 ⼈的课程才统计）。

43.检索⾄少选修两⻔课程的学⽣学号

44.查询选修了全部课程的学⽣信息

45.查询各学⽣的年龄，只按年份来算

46.按照出⽣⽇期来算，当前⽉⽇ < 出⽣年⽉的⽉⽇则，年龄减一

47.查询本周过⽣⽇的学⽣

48.查询下周过⽣⽇的学⽣

49.查询本⽉过⽣⽇的学⽣

50.查询下⽉过⽣⽇的学⽣

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12.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