50条常用语句（以学生表为例）

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

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

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（），马克思（），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 马克思及格百分数

        ,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3 名到第6 名的学生成绩单：企业管理（），马克思（），UML （），数据库（）

    [学生ID],[学生姓名],企业管理,马克思,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 马克思, 

      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    avg(score)>85; 

34、查询课程名称为“数据库”，且分数低于的学生姓名和分数

    SELECT Sname,isnull(score,0) 

    FROM Student,SC,Course 

    WHERE SC.S#=Student.S# AND SC.C#=Course.C# AND  Course.Cname='数据库'and score <60; 

35、查询所有学生的选课情况；

    SELECT SC.S#,SC.C#,Sname,Cname 

    FROM SC,Student,Course 

    WHERE SC.S#=Student.S# AND SC.C#=Course.C# ; 

36、查询任何一门课程成绩在分以上的姓名、课程名称和分数；

    SELECT  distinct student.S#,student.Sname,SC.C#,SC.score 

    FROM student,Sc 

    WHERE SC.score>=70 AND SC.S#=student.S#; 

37、查询不及格的课程，并按课程号从大到小排列

    SELECT c# FROM sc WHERE scor e <60 ORDER BY C# ; 

38、查询课程编号为且课程成绩在分以上的学生的学号和姓名；

    SELECT SC.S#,Student.Sname FROM SC,Student WHERE SC.S#=Student.S# AND Score>80 AND C#='003'; 

39、求选了课程的学生人数

    SELECT count(*) FROM sc; 

40、查询选修“叶平”老师所授课程的学生中，成绩最高的学生姓名及其成绩

    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='叶平' AND SC.score=(SELECT max(score)FROM SC WHERE C#=C.C# ); 

41、查询各个课程及相应的选修人数

    SELECT count(*) FROM sc GROUP BY C#; 

42、查询不同课程成绩相同的学生的学号、课程号、学生成绩

  SELECT distinct  A.S#,B.score FROM SC A  ,SC B WHERE A.Score=B.Score AND A.C# <>B.C# ; 

43、查询每门功成绩最好的前两名

    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 2 score 

              FROM SC 

              WHERE t1.C#= C# 

            ORDER BY score DESC 

              ) 

      ORDER BY t1.C#; 

44、统计每门课程的学生选修人数（超过人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，查询结果按人数降序排列，若人数相同，按课程号升序排列 

    SELECT  C# as 课程号,count(*) as 人数

    FROM  sc  

    group  by  C# 

    order  by  count(*) desc,c#  

45、检索至少选修两门课程的学生学号

    SELECT  S#  

    FROM  sc  

    group  by  s# 

    having  count(*)  >  =  2 

46、查询全部学生都选修的课程的课程号和课程名

    SELECT  C#,Cname  

    FROM  Course  

    WHERE  C#  in  (SELECT  c#  FROM  sc group  by  c#)  

47、查询没学过“叶平”老师讲授的任一门课程的学生姓名

    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='叶平'); 

48、查询两门以上不及格课程的同学的学号及其平均成绩

    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、检索“”课程分数小于，按分数降序排列的同学学号

    SELECT S# FROM SC WHERE C#='004'and score <60 ORDER BY score desc; 

50、删除“”同学的“”课程的成绩

delete FROM Sc WHERE S#='001'and C#='001';