由4张简单的不能再简单的表，演变出50道SQL

(S#,Sname,Sage,Ssex) 学生表

 S# student_no Sage student_age Ssex student_sex

(C#,Cname,T#) 课程表

 C# course_no Cname course_name T# teacher_no

(S#,C#,score) 成绩表

 S# student_no C# course_no score 分数啦

(T#,Tname) 教师表

 T# teacher_no Tname teacher_name

50道问题开始

1、查询“001”课程比“002”课程成绩高的所有学生的学号；

select a.S# from (select s#,score from SC where C#='001') a,(select s#,score

from SC where C#='002'

where a.score>b.score and a.s#=b.s#;

2、查询平均成绩大于60分的同学的学号和平均成绩；

select S#,avg(score)

from sc

group by S# having avg(score) >60;

3、查询所有同学的学号、姓名、选课数、总成绩；

select Student.S#,Student.Sname,count(SC.C#),sum(score)

from Student left Outer join SC on Student.S#=SC.S#

group by Student.S#,Sname

4、查询姓“李”的老师的个数；

select count(distinct(Tname))

from Teacher

where Tname like '%';

5、查询没学过“叶平”老师课的同学的学号、姓名；

select Student.S#,Student.Sname

from Student

where S# not in (select distinct( SC.S#) fromSC,Course,Teacher where  SC.C#=Course.C#and Teacher.T#=Course.T# andTeacher.Tname='叶平');

6、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名；

select Student.S#,Student.Sname fromStudent,SC where Student.S#=SC.S# andSC.C#='001'and exists( Select * from SC as SC_2 where SC_2.S#=SC.S# and SC_2.C#='002');

7、查询学过“叶平”老师所教的所有课的同学的学号、姓名；

select S#,Sname

from Student

where S# in (select S# from SC,Course ,Teacher where SC.C#=Course.C# andTeacher.T#=Course.T# and Teacher.Tname='叶平'group by S# having count(SC.C#)=(select count(C#) fromCourse,Teacher  whereTeacher.T#=Course.T# and Tname='叶平'));

8、查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名；

Select S#,Sname from (select Student.S#,Student.Sname,score ,(select score from SC SC_2 where SC_2.S#=Student.S#and SC_2.C#='002') score2

from Student,SC where Student.S#=SC.S# andC#='001') S_2 where score2 <score;

9、查询所有课程成绩小于60分的同学的学号、姓名；

select S#,Sname

from Student

where S# not in (select Student.S# fromStudent,SC where S.S#=SC.S# andscore>60);

10、查询没有学全所有课的同学的学号、姓名；

select Student.S#,Student.Sname

from Student,SC

whereStudent.S# =SC.S# group by  Student.S#,Student.Sname having count(C#) <( select count(C#) from Course);

11、查询至少有一门课与学号为“1001”的同学所学相同的同学的学号和姓名；

select S#,Sname from Student,SC whereStudent.S#=SC.S# and C# in select C# from SC where S#='1001';

12、查询至少学过学号为“001”同学所有一门课的其他同学学号和姓名；

select distinct SC.S#,Sname

from Student,SC

where Student.S#=SC.S# and C# in(select C# from SC where S#='001');

13、把“SC”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩；

update SC set score=(select avg(SC_2.score)

from SC SC_2

where SC_2.C#=SC.C# ) fromCourse,Teacher where Course.C#=SC.C# andCourse.T#=Teacher.T# and Teacher.Tname='叶平');

14、查询和“1002”号的同学学习的课程完全相同的其他同学学号和姓名；

select S# from SC where C# in(select C# from SC where S#='1002')

group by S# having count(*)=(select count(*) from SC where S#='1002');

15、删除学习“叶平”老师课的SC表记录；

DelectSC

from course ,Teacher

where Course.C#=SC.C# and Course.T#=Teacher.T# and Tname='叶平';

号、2号课的平均成绩；

Insert SC select S#,'002',(Select avg(score)

from SC where C#='002') from Student where S# notin (Select S# from SC where C#='002');

如下形式显示： 学生ID,,数据库,企业管理,英语,有效课程数,有效平均分

SELECT S# as 学生ID

,(SELECT score FROM SC WHERE SC.S#=t.S#AND C#='004') AS 数据库

,(SELECT score FROM SC WHERE SC.S#=t.S#AND C#='001') AS 企业管理

,(SELECT score FROM SC WHERE SC.S#=t.S#AND C#='006') AS 英语

,COUNT(*) AS 有效课程数, AVG(t.score) AS 平均成绩

FROM SC AS t

GROUP BY S#

ORDER BY avg(t.score)

18、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 L.C# As 课程ID,L.score AS 最高分,R.score AS 最低分

FROM SC L ,SC AS R

WHERE L.C# = R.C# and

L.score = (SELECT MAX(IL.score)

FROM SC ASIL,Student AS IM

WHERE L.C# =IL.C# and IM.S#=IL.S#

GROUP BYIL.C#)

AND

R.Score= (SELECT MIN(IR.score)

FROM SC ASIR

WHERE R.C# =IR.C#

GROUP BY IR.C#

);

19、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 t.C# AS 课程号,max(course.Cname)AS 课程名,isnull(AVG(score),0) AS平均成绩

,100 * SUM(CASE WHEN  isnull(score,0)>=60 THEN 1 ELSE 0 END)/COUNT(*) AS 及格百分数

FROM SC T,Course

where t.C#=course.C#

GROUP BY t.C#

ORDER BY 100* SUM(CASE WHEN  isnull(score,0)>=60 THEN 1 ELSE 0 END)/COUNT(*) DESC

企业管理（001），马克思（002），OO&UML （003），数据库（004）

SELECT SUM(CASE WHEN C# ='001' THEN score ELSE 0 END)/SUM(CASE C# WHEN '001' THEN 1 ELSE 0 END) AS 企业管理平均分

,100 * SUM(CASE WHEN C# = '001' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '001' THEN 1 ELSE 0 END) AS 企业管理及格百分数

,SUM(CASE WHEN C# = '002' THEN score ELSE 0 END)/SUM(CASE C# WHEN '002' THEN 1 ELSE 0 END) AS 马克思平均分

,100 * SUM(CASE WHEN C# = '002' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '002' THEN 1 ELSE 0 END) AS 马克思及格百分数

,SUM(CASE WHEN C# = '003' THEN score ELSE 0 END)/SUM(CASE C# WHEN '003' THEN 1 ELSE 0 END) AS UML平均分

,100* SUM(CASE WHEN C# = '003' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '003' THEN 1 ELSE 0 END) AS UML及格百分数

,SUM(CASE WHEN C# = '004' THEN score ELSE 0 END)/SUM(CASE C# WHEN '004' THEN 1 ELSE 0 END) AS 数据库平均分

,100 * SUM(CASE WHEN C# = '004' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '004' THEN 1 ELSE 0 END) AS 数据库及格百分数

FROM SC

21、查询不同老师所教不同课程平均分从高到低显示

  SELECT max(Z.T#) AS 教师ID,MAX(Z.Tname) AS 教师姓名,C.C# AS 课程ＩＤ,MAX(C.Cname) AS 课程名称,AVG(Score) AS 平均成绩
    FROM SC AS T,Course AS C ,Teacher AS Z
    where T.C#=C.C# and C.T#=Z.T#
  GROUP BY C.C#
  ORDER BY AVG(Score) DESC

[学生ID],[学生姓名],企业管理,马克思,UML,数据库,平均成绩

    SELECT  DISTINCT top 3
      SC.S# As 学生学号,
        Student.Sname AS 学生姓名 ,
      T1.score AS 企业管理,
      T2.score AS 马克思,
      T3.score AS UML,
      T4.score AS 数据库,
      ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) as 总分
      FROM Student,SC  LEFT JOIN SC AS T1
                      ON SC.S# = T1.S# AND T1.C# = '001'
            LEFT JOIN SC AS T2
                      ON SC.S# = T2.S# AND T2.C# = '002'
            LEFT JOIN SC AS T3
                      ON SC.S# = T3.S# AND T3.C# = '003'
            LEFT JOIN SC AS T4
                      ON SC.S# = T4.S# AND T4.C# = '004'
      WHERE student.S#=SC.S# and
      ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0)
      NOT IN
      (SELECT
            DISTINCT
            TOP 15 WITH TIES
            ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0)
      FROM sc
            LEFT JOIN sc AS T1
                      ON sc.S# = T1.S# AND T1.C# = 'k1'
            LEFT JOIN sc AS T2
                      ON sc.S# = T2.S# AND T2.C# = 'k2'
            LEFT JOIN sc AS T3
                      ON sc.S# = T3.S# AND T3.C# = 'k3'
            LEFT JOIN sc AS T4
                      ON sc.S# = T4.S# AND T4.C# = 'k4'
      ORDER BY ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) DESC);


23、统计列印各科成绩,各分数段人数:课程ID,课程名称,[100-85],[85-70],[70-60],[ <60]

    SELECT SC.C# as 课程ID, Cname as 课程名称
        ,SUM(CASE WHEN score BETWEEN 85 AND 100 THEN 1 ELSE 0 END) AS [100 - 85]
        ,SUM(CASE WHEN score BETWEEN 70 AND 85 THEN 1 ELSE 0 END) AS [85 - 70]
        ,SUM(CASE WHEN score BETWEEN 60 AND 70 THEN 1 ELSE 0 END) AS [70 - 60]
        ,SUM(CASE WHEN score < 60 THEN 1 ELSE 0 END) AS [60 -]
    FROM SC,Course
    where SC.C#=Course.C#
    GROUP BY SC.C#,Cname;


24、查询学生平均成绩及其名次

      SELECT 1+(SELECT COUNT( distinct 平均成绩)
              FROM (SELECT S#,AVG(score) AS 平均成绩
                      FROM SC
                  GROUP BY S#
                  ) AS T1
            WHERE 平均成绩 > T2.平均成绩) as 名次,
      S# as 学生学号,平均成绩
    FROM (SELECT S#,AVG(score) 平均成绩
            FROM SC
        GROUP BY S#
        ) AS T2
    ORDER BY 平均成绩 desc;


25、查询各科成绩前三名的记录:(不考虑成绩并列情况)

      SELECT t1.S# as 学生ID,t1.C# as 课程ID,Score as 分数
      FROM SC t1
      WHERE score IN (SELECT TOP 3 score
              FROM SC
              WHERE t1.C#= C#
            ORDER BY score DESC
              )
      ORDER BY t1.C#;

26、查询每门课程被选修的学生数

  select c#,count(S#) from sc group by C#;

27、查询出只选修了一门课程的全部学生的学号和姓名

  select SC.S#,Student.Sname,count(C#) AS 选课数
  from SC ,Student
  where SC.S#=Student.S# group by SC.S# ,Student.Sname having count(C#)=1;


28、查询男生、女生人数

    Select count(Ssex) as 男生人数 from Student group by Ssex having Ssex='男';
    Select count(Ssex) as 女生人数 from Student group by Ssex having Ssex='女'；

29、查询姓“张”的学生名单

    SELECT Sname FROM Student WHERE Sname like '张%';


30、查询同名同性学生名单，并统计同名人数

  select Sname,count(*) from Student group by Sname having  count(*)>1;

31、1981年出生的学生名单(注：Student表中Sage列的类型是datetime)

    select Sname,  CONVERT(char (11),DATEPART(year,Sage)) as age
    from student
    where  CONVERT(char(11),DATEPART(year,Sage))='1981';

32、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 C#,Avg(score) from SC group by C# order by Avg(score),C# DESC ;

33、查询平均成绩大于85的所有学生的学号、姓名和平均成绩

    select Sname,SC.S# ,avg(score)
    from Student,SC
    where Student.S#=SC.S# group by SC.S#,Sname having    avg(score)>85;


34、查询课程名称为“数据库”，且分数低于60的学生姓名和分数

    Select Sname,isnull(score,0)
    from Student,SC,Course
    where SC.S#=Student.S# and SC.C#=Course.C# and  Course.Cname='数据库'and score <60;


35、查询所有学生的选课情况；

    SELECT SC.S#,SC.C#,Sname,Cname
    FROM SC,Student,Course
    where SC.S#=Student.S# and SC.C#=Course.C# ;


36、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  distinct student.S#,student.Sname,SC.C#,SC.score
    FROM student,Sc
    WHERE SC.score>=70 AND SC.S#=student.S#;

37、查询不及格的课程，并按课程号从大到小排列

    select c# from sc where scor e <60 order by C# ;


38、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名；

    select SC.S#,Student.Sname from SC,Student where SC.S#=Student.S# and Score>80 and C#='003';

39、求选了课程的学生人数

select count( *) from sc;

40、查询选修“叶平”老师所授课程的学生中，成绩最高的学生姓名及其成绩

    select Student.Sname,score
    from Student,SC,Course C,Teacher
    where Student.S#=SC.S# and SC.C#=C.C# and C.T#=Teacher.T# and Teacher.Tname='叶平' and SC.score=(select max(score)from SC where C#=C.C# );

41、查询各个课程及相应的选修人数

    select count(*) from sc group by C#;

42、查询不同课程成绩相同的学生的学号、课程号、学生成绩

  select distinct  A.S#,B.score from SC A  ,SC B where A.Score=B.Score and A.C# <>B.C# ;

43、查询每门功成绩最好的前两名

    SELECT t1.S# as 学生ID,t1.C# as 课程ID,Score as 分数
      FROM SC t1
      WHERE score IN (SELECT TOP 2 score
              FROM SC
              WHERE t1.C#= C#
            ORDER BY score DESC
              )
      ORDER BY t1.C#;

44、统计每门课程的学生选修人数（超过10人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，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  C# as 课程号,count(*) as 人数
    from  sc
    group  by  C#
    order  by  count(*) desc,c#

45、检索至少选修两门课程的学生学号

    select  S#
    from  sc
    group  by  s#
    having  count(*)  >  =  2

46、查询全部学生都选修的课程的课程号和课程名

    select  C#,Cname
    from  Course
    where  C#  in  (select  c#  from  sc group  by  c#)

47、查询没学过“叶平”老师讲授的任一门课程的学生姓名

    select Sname from Student where S# not in (select S# from Course,Teacher,SC where Course.T#=Teacher.T# and SC.C#=course.C# and Tname='叶平');

48、查询两门以上不及格课程的同学的学号及其平均成绩

    select S#,avg(isnull(score,0)) from SC where S# in (select S# from SC where score <60 group by S# having count(*)>2)group by S#;

49、检索“004”课程分数小于60，按分数降序排列的同学学号

    select S# from SC where C#='004'and score <60 order by score desc;

50、删除“002”同学的“001”课程的成绩

delete from Sc where S# = '001' and C# = '001'

|
22天前
|

Java多线程面试题总结(上)

28 2
|
22天前
|

Java面向对象面试题总结(上)

18 1
|
23天前
|
NoSQL Java 数据库
2022年整理最详细的java面试题、掌握这一套八股文、面试基础不成问题[吐血整理、纯手撸]

30 0
|
12天前
|
C# Windows 开发者

【8月更文挑战第31天】本文详细介绍了如何在Windows Presentation Foundation (WPF) 中集成OpenGL，以实现高性能的跨平台图形处理。通过具体示例代码，展示了使用SharpGL库在WPF应用中创建并渲染OpenGL图形的过程，包括开发环境搭建、OpenGL渲染窗口创建及控件集成等关键步骤，帮助开发者更好地理解和应用OpenGL技术。
52 0
|
20天前
|
Java 编译器 开发工具
JDK vs JRE：面试大揭秘，一文让你彻底解锁Java开发和运行的秘密！
【8月更文挑战第24天】JDK（Java Development Kit）与JRE（Java Runtime Environment）是Java环境中两个核心概念。JDK作为开发工具包，不仅包含JRE，还提供编译器等开发工具，支持Java程序的开发与编译；而JRE仅包含运行Java程序所需的组件如JVM和核心类库。一个简单的&quot;Hello, World!&quot;示例展示了两者用途：需借助JDK编译程序，再利用JRE或JDK中的运行环境执行。因此，开发者应基于实际需求选择安装JDK或JRE。
37 0
|
22天前
|

Java多线程面试题总结(中)
Java内存模型（JMM）定义了程序中所有变量的访问规则与范围，确保多线程环境下的数据一致性。JMM包含主内存与工作内存的概念，通过8种操作管理两者间的交互，确保原子性、可见性和有序性。synchronized和volatile关键字提供同步机制，前者确保互斥访问，后者保证变量更新的可见性。多线程操作涉及不同状态，如新建（NEW）、可运行（RUNNABLE）等，并可通过中断、等待和通知等机制协调线程活动。volatile虽不确保线程安全，但能确保变量更新对所有线程可见。
15 0
|
22天前
|

Java基础面试题总结(上)
Java有8种基本数据类型：byte(1字节)、short(2字节)、int(4字节)、long(8字节)、float(4字节)、double(8字节)、boolean、char(2字节)。String类被final修饰，不可被继承。String为只读，内容不可改；StringBuffer和StringBuilder可修改内容，前者线程安全，后者非线程安全，故效率更高。
13 0
|
23天前
|

【多线程面试题十八】、说一说Java中乐观锁和悲观锁的区别

18 0
|
23天前
|

【多线程面试题 八】、说一说Java同步机制中的wait和notify
Java同步机制中的wait()、notify()、notifyAll()是Object类的方法，用于线程间的通信，其中wait()使当前线程释放锁并进入阻塞状态，notify()唤醒单个等待线程，notifyAll()唤醒所有等待线程。
26 0
|
23天前
|

【IO面试题 四】、介绍一下Java的序列化与反序列化
Java的序列化与反序列化允许对象通过实现Serializable接口转换成字节序列并存储或传输，之后可以通过ObjectInputStream和ObjectOutputStream的方法将这些字节序列恢复成对象。
29 2