数据库基本操作 - 数据库编程

CT 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))='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 scor e <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#='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#

数据库基本操作(四)