常用sql語句練習-2

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';