网上流行的学生选课相关的50个常用sql语句

学生表 Student(S#,Sname,Sage,Ssex)

教师表 Teacher(T#,Tname)

课程表 Course(C#,Cname,T#)

学生成绩表 SC(S#,C#,score)

问题：

1、查询“001”课程比“002”课程成绩高的所有学生的学号;

SELECT  a.s#
FROM    ( SELECT    *
          FROM      dbo.SC
          WHERE     c# = ''
        ) a
        INNER JOIN ( SELECT *
                     FROM   dbo.SC
                     WHERE  c# = ''
                   ) b ON a.s# = b.s#
WHERE   a.score > b.score

2、查询平均成绩大于60分的同学的学号和平均成绩;

SELECT  s# ,
        AVG(score)
FROM    dbo.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  a.s# ,
        a.sname ,
        COUNT(b.c#) ,
        SUM(b.score)
FROM    dbo.Student a
        LEFT OUTER JOIN dbo.SC b ON a.s# = b.s#
GROUP BY a.s# ,
        a.sname

4、查询姓“李”的老师的个数;

SELECT  COUNT(DISTINCT tname)
FROM    dbo.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“001”并且也学过编号“002”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# = ''
        AND EXISTS ( SELECT *
                     FROM   SC AS SC_2
                     WHERE  SC_2.S# = SC.S#
                            AND SC_2.C# = '' )

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“002”的成绩比课程编号“001”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# = ''
                    ) score2
          FROM      Student ,
                    SC
          WHERE     Student.S# = SC.S#
                    AND C# = ''
        ) S_2
WHERE   score2 < score

9、查询所有课程成绩小于60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   Student.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“1001”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# = '' )

12、查询至少学过学号为“001”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# = '' )

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“1002”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# = '' )
GROUP BY S#
HAVING  COUNT(*) = ( SELECT COUNT(*)
                     FROM   SC
                     WHERE  S# = ''
                   )

15、删除学习“叶平”老师课的SC表记录;

DELETE  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“003”课程的同学学号、2、 号课的平均成绩;

INSERT  SC
        SELECT  S# ,
                '' ,
                ( SELECT    AVG(score)
                  FROM      SC
                  WHERE     C# = ''
                )
        FROM    Student
        WHERE   S# NOT IN ( SELECT  S#
                            FROM    SC
                            WHERE   C# = '' )

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# = ''
        ) AS 数据库 ,
        ( SELECT    score
          FROM      SC
          WHERE     SC.S# = t.S#
                    AND C# = ''
        ) AS 企业管理 ,
        ( SELECT    score
          FROM      SC
          WHERE     SC.S# = t.S#
                    AND C# = ''
        ) 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（001），马克思（002），OO&UML （003），数据库（004）

SELECT SUM(CASE WHEN C# ='' THEN score ELSE 0 END)/SUM(CASE C# WHEN '' THEN 1 ELSE 0 END) AS 企业管理平均分
,100 * SUM(CASE WHEN C# = '' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '' THEN 1 ELSE 0 END) AS 企业管理及格百分数
,SUM(CASE WHEN C# = '' THEN score ELSE 0 END)/SUM(CASE C# WHEN '' THEN 1 ELSE 0 END) AS 马克思平均分
,100 * SUM(CASE WHEN C# = '' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '' THEN 1 ELSE 0 END) AS 马克思及格百分数
,SUM(CASE WHEN C# = '' THEN score ELSE 0 END)/SUM(CASE C# WHEN '' THEN 1 ELSE 0 END) AS UML平均分
,100 * SUM(CASE WHEN C# = '' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '' THEN 1 ELSE 0 END) AS UML及格百分数
,SUM(CASE WHEN C# = '' THEN score ELSE 0 END)/SUM(CASE C# WHEN '' THEN 1 ELSE 0 END) AS 数据库平均分
,100 * SUM(CASE WHEN C# = '' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '' 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（001），马克思（002），UML （003），数据库（004） [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# = ''
LEFT JOIN SC AS T2
ON SC.S# = T2.S# AND T2.C# = ''
LEFT JOIN SC AS T3
ON SC.S# = T3.S# AND T3.C# = ''
LEFT JOIN SC AS T4
ON SC.S# = T4.S# AND T4.C# = ''
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、1981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))=''; 

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85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60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70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 score <60 order by C# ; 

38、查询课程编号为003且课程成绩在80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#=''; 

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 c#,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10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“004”课程分数小于60，按分数降序排列的同学学号

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

50、删除“002”同学的“001”课程的成绩

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