Sql Server专题：SQL 经典实例

SQL 经典实例

1、实例表：

Student(S#,Sname,Sage,Ssex) 学生表         

S#：学号；Sname：学生姓名；Sage：学生年龄；Ssex：学生性别

Course(C#,Cname,T#) 课程表                   

C#,课程编号；Cname：课程名字；T#：教师编号

SC(S#,C#,score) 成绩表                           

S#：学号；C#,课程编号；score：成绩

Teacher(T#,Tname) 教师表                       

T#：教师编号； Tname：教师名字

2、问题：

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

2、查询平均成绩大于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 '李%';　

5、查询没学过“叶平”老师课的同学的学号、姓名；

 select Student.S#,Student.Snamefrom Student
 where S# not in (select distinct( SC.S#) from SC,Course,Teacher where  SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.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 from Student,SC where Student.S#=SC.S# and SC.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# and Teacher.T#=Course.T# and Teacher.Tname='叶平'
group by S# having count(SC.C#)=(select count(C#) from Course,Teacher  where Teacher.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# and C#='001') S_2 where score2 

9、查询所有课程成绩小于分的同学的学号、姓名；

select S#,Sname from Student
where S# not in (select Student.S# from Student,SC where S.S#=SC.S# and score>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
 where Student.S#=SC.S#
 group by  Student.S#,Student.Sname
 having count(C#) <(select count(DISTINCT 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 DISTINCT Student.S#,Sname from Student,SC
 where Student.S#=SC.S# and C# in (select C# from SC where S#=1)
 ORDER BY Student.S# ASC;　

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# ) from Course,Teacher where Course.C#=SC.C# and   Course.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；

 Delect SC from course ,Teacher
 where Course.C#=SC.C# and Course.T#= Teacher.T# and Tname='叶平';　

16、向SC表中插入一些记录，这些记录要求符合以下条件：没有上过编号“003”课程的同学学号002号课的平均成绩；

Insert SC select S#,'002',(Select avg(score)
from SC where C#='002') from Student where S# not in (Select S# from SC where C#='002');
SELECT (SELECT SC.S# FROM SC WHERE SC.S# NOT IN(SELECT SC.S# FROM SC WHERE SC.C#=202 )),202,(SELECT AVG(SC.score) FROM SC WHERE SC.C#=203)

17、按平均成绩从高到低显示所有学生的“数据库”、“企业管理”、“英语”三门的课程成绩，按如下形式显示： 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 c#,MAX(sc.score) ,Min(sc.score) as 最高分 from SC group by 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

select sc0.C#,avg(sc0.score) as 平均成绩,
cast (
((select COUNT(*) from SC where sc.score>60  and sc0.C#=sc.C# )*1.0/
  (select COUNT(*) from SC where sc0.C#=sc.C# )*100
)   as  decimal(38 , 2))
as 及格率
from SC  sc0
group by sc0.C#
order by  avg(sc0.score)  desc

20、查询如下课程平均成绩和及格率的百分数(用"1行"显示): 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　

22、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;　

23、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;

24、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#;　

25、查询每门课程被选修的学生数

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

26、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;

27、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;

28、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';　　

29、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 ;　

30、查询平均成绩大于的所有学生的学号、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;　

31、查询课程名称为“数据库”，且分数低于的学生姓名和分数

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;　

32、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# 

33、查询任何一门课程成绩在分以上的姓名、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#;　

34、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# ;

35、查询课程编号为且课程成绩在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';

36、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# );　　

37、查询各个课程及相应的选修人数

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

38、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# ;

39、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#;　　

40、统计每门课程的学生选修人数（超过人的课程才统计）。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#　

41、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　

42、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#)

43、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');　

44、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#;

45、检索“004”课程分数小于，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;

　　

 

转载于:https://www.cnblogs.com/java-oracle/p/5382283.html