SQL學習及回顧第一篇總結

初始條件：

Student(S#,Sname,Sage,Ssex) 學生表 

Course(C#,Cname,T#) 課程表 
SC(S#,C#,score) 成績表 
Teacher(T#,Tname) 教師表 


問題： 
1、查詢“001”課程比“002”課程成績高的所有學生的學號； 
  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、查詢平均成績大於60分的同學的學號和平均成績； 

    select S#,avg(score) 
    from sc 
    group by S# having avg(score) >60; 

3、查詢所有同學的學號、姓名、選課數、總成績； 

  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、查詢姓“李”的老師的個數； 

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

5、查詢沒學過“葉平”老師課的同學的學號、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='葉平'); 

6、查詢學過“001”並且也學過編號“002”課程的同學的學號、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、查詢學過“葉平”老師所教的所有課的同學的學號、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='葉平' group by S# having count(SC.C#)=(select count(C#) from Course,Teacher  where Teacher.T#=Course.T# and Tname='葉平')); 

8、查詢課程編號“002”的成績比課程編號“001”課程低的所有同學的學號、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、查詢所有課程成績小於60分的同學的學號、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、查詢沒有學全所有課的同學的學號、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、查詢至少有一門課與學號爲“1001”的同學所學相同的同學的學號和姓名； 

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

12、查詢至少學過學號爲“001”同學所有一門課的其他同學學號和姓名； 

    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“葉平”老師教的課的成績都更改爲此課程的平均成績； 

    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='葉平'); 

14、查詢和“1002”號的同學學習的課程完全相同的其他同學學號和姓名； 

    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、刪除學習“葉平”老師課的SC表記錄； 

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

16、向SC表中插入一些記錄，這些記錄要求符合以下條件：沒有上過編號“003”課程的同學學號、2、 

    號課的平均成績； 
    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、按平均成績從高到低顯示所有學生的“數據庫”、“企業管理”、“英語”三門的課程成績，按如下形式顯示： 學生ID,,數據庫,企業管理,英語,有效課程數,有效平均分 

    SELECT S# as 學生ID 
        ,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#='004') AS 數據庫 
        ,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#='001') AS 企業管理 
        ,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#='006') AS 英語 
        ,COUNT(*) AS 有效課程數, AVG(t.score) AS 平均成績 
    FROM SC AS t 
    GROUP BY S# 
    ORDER BY avg(t.score)  

18、查詢各科成績最高和最低的分：以如下形式顯示：課程ID，最高分，最低分 

    SELECT L.C# As 課程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、按各科平均成績從低到高和及格率的百分數從高到低順序 

    SELECT t.C# AS 課程號,max(course.Cname)AS 課程名,isnull(AVG(score),0) AS 平均成績 
        ,100 * SUM(CASE WHEN  isnull(score,0)>=60 THEN 1 ELSE 0 END)/COUNT(*) AS 及格百分數 
    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、查詢如下課程平均成績和及格率的百分數(用"1行"顯示): 企業管理（001），馬克思（002），OO&UML （003），數據庫（004） 

    SELECT SUM(CASE WHEN C# ='001' THEN score ELSE 0 END)/SUM(CASE C# WHEN '001' THEN 1 ELSE 0 END) AS 企業管理平均分 
        ,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 企業管理及格百分數 
        ,SUM(CASE WHEN C# = '002' THEN score ELSE 0 END)/SUM(CASE C# WHEN '002' THEN 1 ELSE 0 END) AS 馬克思平均分 
        ,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 馬克思及格百分數 
        ,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及格百分數 
        ,SUM(CASE WHEN C# = '004' THEN score ELSE 0 END)/SUM(CASE C# WHEN '004' THEN 1 ELSE 0 END) AS 數據庫平均分 
        ,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 數據庫及格百分數 
  FROM SC 

21、查詢不同老師所教不同課程平均分從高到低顯示 

  SELECT max(Z.T#) AS 教師ID,MAX(Z.Tname) AS 教師姓名,C.C# AS 課程ＩＤ,MAX(C.Cname) AS 課程名稱,AVG(Score) AS 平均成績 
    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、查詢如下課程成績第 3 名到第 6 名的學生成績單：企業管理（001），馬克思（002），UML （003），數據庫（004） 

    [學生ID],[學生姓名],企業管理,馬克思,UML,數據庫,平均成績 
    SELECT  DISTINCT top 3 
      SC.S# As 學生學號, 
        Student.Sname AS 學生姓名 , 
      T1.score AS 企業管理, 
      T2.score AS 馬克思, 
      T3.score AS UML, 
      T4.score AS 數據庫, 
      ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) as 總分 
      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、統計列印各科成績,各分數段人數:課程ID,課程名稱,[100-85],[85-70],[70-60],[ <60] 
    SELECT SC.C# as 課程ID, Cname as 課程名稱 
        ,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、查詢學生平均成績及其名次 
      SELECT 1+(SELECT COUNT( distinct 平均成績) 
              FROM (SELECT S#,AVG(score) AS 平均成績 
                      FROM SC 
                  GROUP BY S# 
                  ) AS T1 
            WHERE 平均成績 > T2.平均成績) as 名次, 
      S# as 學生學號,平均成績 
    FROM (SELECT S#,AVG(score) 平均成績 
            FROM SC 
        GROUP BY S# 
        ) AS T2 
    ORDER BY 平均成績 desc; 
  
25、查詢各科成績前三名的記錄:(不考慮成績並列情況) 
      SELECT t1.S# as 學生ID,t1.C# as 課程ID,Score as 分數 
      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、查詢每門課程被選修的學生數 

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

27、查詢出只選修了一門課程的全部學生的學號和姓名 

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

28、查詢男生、女生人數 

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

29、查詢姓“張”的學生名單 

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

30、查詢同名同性學生名單，並統計同名人數 

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

31、1981年出生的學生名單(注：Student表中Sage列的類型是datetime) 

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

32、查詢每門課程的平均成績，結果按平均成績升序排列，平均成績相同時，按課程號降序排列 

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

33、查詢平均成績大於85的所有學生的學號、姓名和平均成績 

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

34、查詢課程名稱爲“數據庫”，且分數低於60的學生姓名和分數 

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

35、查詢所有學生的選課情況； 

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

36、查詢任何一門課程成績在70分以上的姓名、課程名稱和分數； 

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

37、查詢不及格的課程，並按課程號從大到小排列 

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

38、查詢課程編號爲003且課程成績在80分以上的學生的學號和姓名； 

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

39、求選了課程的學生人數 

    select count(*) from sc; 

40、查詢選修“葉平”老師所授課程的學生中，成績最高的學生姓名及其成績 

    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='葉平' and SC.score=(select max(score)from SC where C#=C.C# ); 

41、查詢各個課程及相應的選修人數 

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

42、查詢不同課程成績相同的學生的學號、課程號、學生成績 

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

43、查詢每門功成績最好的前兩名 

    SELECT t1.S# as 學生ID,t1.C# as 課程ID,Score as 分數 
      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、統計每門課程的學生選修人數（超過10人的課程才統計）。要求輸出課程號和選修人數，查詢結果按人數降序排列，查詢結果按人數降序排列，若人數相同，按課程號升序排列  

    select  C# as 課程號,count(*) as 人數 
    from  sc  
    group  by  C# 
    order  by  count(*) desc,c#  

45、檢索至少選修兩門課程的學生學號 

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

46、查詢全部學生都選修的課程的課程號和課程名 

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

47、查詢沒學過“葉平”老師講授的任一門課程的學生姓名 

    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='葉平'); 

48、查詢兩門以上不及格課程的同學的學號及其平均成績 

    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、檢索“004”課程分數小於60，按分數降序排列的同學學號 

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

50、刪除“002”同學的“001”課程的成績 

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