常用的学生、课程、成绩、教师表的查询

Student(S#,Sname,Sage,Ssex) 学生表
Course(C#,Cname,T#) 课程表
SC(S#,C#,score) 成绩表
Teacher(T#,Tname) 教师表
 
create table Student(S# varchar(20),Sname varchar(10),Sage int,Ssex varchar(2)) 
前面加一列序号：
if
exists(select table_name from information_schema.tables
  where table_name='Temp_Table')
drop table Temp_Table
go
select 排名=identity(int,1,1),* INTO   Temp_Table    from Student 
go
select * from Temp_Table
go 
 
drop database [ ]  --删除空的没有名字的数据库
问题：
1、查询“”课程比“”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.Sname 
    from 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“”并且也学过编号“”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“”的成绩比课程编号“”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 <score; 
 
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(C#) from Course); 
 
11、查询至少有一门课与学号为“”的同学所学相同的同学的学号和姓名；
    select S#,Sname from Student,SC where Student.S#=SC.S# and C# in select C# from SC where S#='1001'; 
 
12、查询至少学过学号为“”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“”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“”课程的同学学号、、
    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'); 
 
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 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 AS IL,Student AS IM 
                      WHERE L.C# = IL.C# and IM.S#=IL.S# 
                      GROUP BY IL.C#) 
        AND 
        R.Score = (SELECT MIN(IR.score) 
                      FROM SC AS IR 
                      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 
 
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（），马克（），OO&UML （），数据库（）
    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、查询如下课程成绩第名到第名的学生成绩单：企业管理（），马克（），UML （），数据库（）
    [学生ID],[学生姓名],企业管理,马克,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, 
      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、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