常用的sql語句總結

這篇文章主要介紹“常用的sql語句總結”，在日常操作中，相信很多人在常用的sql語句總結問題上存在疑惑，小編查閱了各式資料，整理出簡單好用的操作方法，希望對大家解答”常用的sql語句總結”的疑惑有所幫助！接下來，請跟著小編一起來學習吧！

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、查詢平均成績大于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”并且也學過編號“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于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為“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、查詢至少學過學號為“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為此課程的平均成績;
    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:(不考慮成績并列情況)
      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 ,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，并統計同名人數
  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、查詢平均成績大于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、查詢課程名稱為“”，且分數低于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，并按課程號從大到小排列
    select c# from sc where scor e <60 order by C# ;
38、查詢課程編號為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”課程分數小于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';
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、查詢平均成績大于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”并且也學過編號“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于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為“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、查詢至少學過學號為“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為此課程的平均成績;
    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:(不考慮成績并列情況)
      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，并統計同名人數
  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、查詢平均成績大于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、查詢課程名稱為“數據庫”，且分數低于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，并按課程號從大到小排列
    select c# from sc where scor e <60 order by C# ;
38、查詢課程編號為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”課程分數小于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';

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