SQL經典50句（前25）

經典SQL 50句

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：  
一、查詢「001」課程比「002」課程成績高的全部學生的學號；  

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#;

二、查詢平均成績大於60分的同窗的學號和平均成績；    

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

三、查詢全部同窗的學號、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

   
四、查詢姓「李」的老師的個數；    
  

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

五、查詢沒學過「葉平」老師課的同窗的學號、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');

六、查詢學過「001」而且也學過編號「002」課程的同窗的學號、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');

七、查詢學過「葉平」老師所教的全部課的同窗的學號、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'));

   
八、查詢課程編號「002」的成績比課程編號「001」課程低的全部同窗的學號、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;

九、查詢全部課程成績小於60分的同窗的學號、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);

十、查詢沒有學全全部課的同窗的學號、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);

   
十一、查詢至少有一門課與學號爲「1001」的同窗所學相同的同窗的學號和姓名；    
    

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

十二、查詢至少學過學號爲「001」同窗全部一門課的其餘   同窗學號和姓名；    
    

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

1三、把「SC」表中「葉平」老師教的課的成績都更改成此課程的平均成績；    
   

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');

1四、查詢和「1002」號的同窗學習   的課程徹底相同的其餘同窗學號和姓名；    
    

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');

1五、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';

1六、向SC表中插入一些記錄，這些記錄要求符合如下條件：沒有上過編號「003」課程的同窗學號、二、    
    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');

1七、按平均成績從高到低顯示全部學生的「數據庫   」、「企業管理」、「英語」三門的課程成績，按以下形式顯示： 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)

1八、查詢各科成績最高和最低的分：以以下形式顯示：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#  
                    );

1九、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、查詢以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

2一、查詢不一樣老師所教不一樣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

2二、查詢以下課程成績第 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);

2三、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;

2四、查詢學平生均成績及其名次    
     

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;

    
2五、查詢各科成績前三名的記錄:(不考慮成績並列狀況)    
   

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#;