爱是王道 发表于 2018-10-21 09:53:52

数据库SQL基本功练习

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
  SELECTDISTINCT 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,SCLEFT 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,,,,[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 havingcount(*)>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
  whereCONVERT(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# andCourse.Cname='数据库'and 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 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 distinctA.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
  selectC# as 课程号,count(*) as 人数
  fromsc
  groupbyC#
  orderbycount(*) desc,c#
  45、检索至少选修两门课程的学生学号
  selectS#
  fromsc
  groupbys#
  havingcount(*)>=2 46、查询全部学生都选修的课程的课程号和课程名
  selectC#,Cname
  fromCourse
  whereC#in(selectc#fromsc groupbyc#)
  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 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#='004'and score
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