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SQL面试笔试优质题,优秀面试题及答案

发布时间:2019-11-09 07:56编辑:网络数据库浏览(120)

    本文是在Cat Qi的原贴的基础之上,经本人逐题分别在MySql数据库中实现的笔记,持续更新...**

    SQL数据库面试题以及答案

    Student(Sno,Sname,Sage,Ssex) 学生表       Sno:学号;Sname:学生姓名;Sage:学生年龄;Ssex:学生性别
    Course(Cno,Cname,Tno) 课程表                    Cno,课程编号;Cname:课程名字;Tno:教师编号
    SC(Sno,Cno,score) 成绩表                             Sno:学号;Cno,课程编号;score:成绩
    Teacher(Tno,Tname) 教师表                        Tno:教师编号; Tname:教师名字

     

    创建数据表:

    create table Student(

    Sno varchar(10) not null primary key,

    Sname varchar(20) null,

    Sage int null,

    Ssex varchar(2) null

    )

    create table Course(

    Cno varchar(10) not null primary key,

    Cname varchar(20) null,

    Tno varchar(20) null

    )

    create table SC(

    Sno varchar(10) not null primary key,

    Cno varchar(10) not null primary key,

    score int null

    )

    create table Teacher(

    Tno varchar(20) primary key not null,

    Tname varchar(20) null

    )

    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.Sno from (select Sno,score from SC where Cno='001') a,(select Sno,score
      from SC where Cno='002') b
      where a.score>b.score and a.Sno=b.Sno;
    2、查询平均成绩大于60分的同学的学号和平均成绩;
        select Sno,avg(score)
        from sc
        group by Sno having avg(score) >60;
    3、查询所有同学的学号、姓名、选课数、总成绩;
      select Student.Sno,Student.Sname,count(SC.Cno),sum(score)
      from Student left Outer join SC on Student.Sno=SC.Sno
      group by Student.Sno,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.Sno,Student.Sname
        from Student 
        where Sno not in (select distinct( SC.Sno) from SC,Course,Teacher where SC.Cno=Course.Cno and Teacher.Tno=Course.Tno  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.Sno,Student.Sname from Student,SC where Student.Sno=SC.Sno and SC.Cno='001'and exists( Select * from SC as SC_2 where SC_2.Sno=SC.Sno and SC_2.Cno='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 Sno,Sname
      from Student
      where Sno in (select Sno from SC ,Course ,Teacher where SC.Cno=Course.Cno and Teacher.Tno=Course.Tno and Teacher.Tname='叶平' group by Sno having count(SC.Cno)=(select count(Cno) from Course,Teacher  where Teacher.Tno=Course.Tno 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 Sno,Sname from (select Student.Sno,Student.Sname,score ,(select score from SC SC_2 where SC_2.Sno=Student.Sno and SC_2.Cno='002') score2
      from Student,SC where Student.Sno=SC.Sno and Cno='001') 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 Sno,Sname
      from Student
      where Sno not in (select Student.Sno from Student,SC where S.Sno=SC.Sno and score>60);
    10、查询没有学全所有课的同学的学号、姓名;
        select Student.Sno,Student.Sname
        from Student,SC
        where Student.Sno=SC.Sno group by  Student.Sno,Student.Sname having count(Cno) <(select count(Cno) 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 Sno,Sname from Student,SC where Student.Sno=SC.Sno and Cno in select Cno from SC where Sno='1001';
    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.Sno,Sname
        from Student,SC
        where Student.Sno=SC.Sno and Cno in (select Cno from SC where Sno='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.Cno=SC.Cno ) from Course,Teacher where Course.Cno=SC.Cno and Course.Tno=Teacher.Tno 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 Sno from SC where Cno in (select Cno from SC where Sno='1002')
        group by Sno having count(*)=(select count(*) from SC where Sno='1002');
    15、删除学习“叶平”老师课的SC表记录;
        Delect SC
        from course ,Teacher 
        where Course.Cno=SC.Cno and Course.Tno= Teacher.Tno 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 Sno,'002',(Select avg(score)
        from SC where Cno='002') from Student where Sno not in (Select Sno from SC where Cno='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 Sno as 学生ID
            ,(SELECT score FROM SC WHERE SC.Sno=t.Sno AND Cno='004') AS 数据库
            ,(SELECT score FROM SC WHERE SC.Sno=t.Sno AND Cno='001') AS 企业管理
            ,(SELECT score FROM SC WHERE SC.Sno=t.Sno AND Cno='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 Sno
        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.Cno As 课程ID,L.score AS 最高分,R.score AS 最低分
        FROM SC L ,SC AS R
        WHERE L.Cno = R.Cno and
            L.score = (SELECT MAX(IL.score)
                          FROM SC AS IL,Student AS IM
                          WHERE L.Cno = IL.Cno and IM.Sno=IL.Sno
                          GROUP BY IL.Cno)
            AND
            R.Score = (SELECT MIN(IR.score)
                          FROM SC AS IR
                          WHERE R.Cno = IR.Cno
                      GROUP BY IR.Cno
                        );
    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.Cno 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.Cno=course.Cno
        GROUP BY t.Cno
        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 Cno ='001' THEN score ELSE 0 END)/SUM(CASE Cno WHEN '001' THEN 1 ELSE 0 END) AS 企业管理平均分
            ,100 * SUM(CASE WHEN Cno = '001' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN Cno = '001' THEN 1 ELSE 0 END) AS 企业管理及格百分数
            ,SUM(CASE WHEN Cno = '002' THEN score ELSE 0 END)/SUM(CASE Cno WHEN '002' THEN 1 ELSE 0 END) AS 马克思平均分
            ,100 * SUM(CASE WHEN Cno = '002' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN Cno = '002' THEN 1 ELSE 0 END) AS 马克思及格百分数
            ,SUM(CASE WHEN Cno = '003' THEN score ELSE 0 END)/SUM(CASE Cno WHEN '003' THEN 1 ELSE 0 END) AS UML平均分
            ,100 * SUM(CASE WHEN Cno = '003' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN Cno = '003' THEN 1 ELSE 0 END) AS UML及格百分数
            ,SUM(CASE WHEN Cno = '004' THEN score ELSE 0 END)/SUM(CASE Cno WHEN '004' THEN 1 ELSE 0 END) AS 数据库平均分
            ,100 * SUM(CASE WHEN Cno = '004' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN Cno = '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.Tno) AS 教师ID,MAX(Z.Tname) AS 教师姓名,C.Cno 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.Cno=C.Cno and C.Tno=Z.Tno
      GROUP BY C.Cno
      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.Sno 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.Sno = T1.Sno AND T1.Cno = '001'
                LEFT JOIN SC AS T2
                          ON SC.Sno = T2.Sno AND T2.Cno = '002'
                LEFT JOIN SC AS T3
                          ON SC.Sno = T3.Sno AND T3.Cno = '003'
                LEFT JOIN SC AS T4
                          ON SC.Sno = T4.Sno AND T4.Cno = '004'
          WHERE student.Sno=SC.Sno 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.Sno = T1.Sno AND T1.Cno = 'k1'
                  LEFT JOIN sc AS T2
                            ON sc.Sno = T2.Sno AND T2.Cno = 'k2'
                  LEFT JOIN sc AS T3
                            ON sc.Sno = T3.Sno AND T3.Cno = 'k3'
                  LEFT JOIN sc AS T4
                            ON sc.Sno = T4.Sno AND T4.Cno = '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.Cno 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.Cno=Course.Cno
        GROUP BY SC.Cno,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 Sno,AVG(score) AS 平均成绩
                          FROM SC
                      GROUP BY Sno
                      ) AS T1
                WHERE 平均成绩 > T2.平均成绩) as 名次,
          Sno as 学生学号,平均成绩
        FROM (SELECT Sno,AVG(score) 平均成绩
                FROM SC
            GROUP BY Sno
            ) 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.Sno as 学生ID,t1.Cno as 课程ID,Score as 分数
          FROM SC t1
          WHERE score IN (SELECT TOP 3 score
                  FROM SC
                  WHERE t1.Cno= Cno
                ORDER BY score DESC
                  )
          ORDER BY t1.Cno;
    26、查询每门课程被选修的学生数
      select Cno,count(Sno) from sc group by Cno;
    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.Sno,Student.Sname,count(Cno) AS 选课数
      from SC ,Student
      where SC.Sno=Student.Sno group by SC.Sno ,Student.Sname having count(Cno)=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 Cno,Avg(score) from SC group by Cno order by Avg(score),Cno 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.Sno ,avg(score)
        from Student,SC
        where Student.Sno=SC.Sno group by SC.Sno,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.Sno=Student.Sno and SC.Cno=Course.Cno and  Course.Cname='数据库'and score <60;
    35、查询所有学生的选课情况;
        SELECT SC.Sno,SC.Cno,Sname,Cname
        FROM SC,Student,Course
        where SC.Sno=Student.Sno and SC.Cno=Course.Cno ;
    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.Sno,student.Sname,SC.Cno,SC.score
        FROM student,Sc
        WHERE SC.score>=70 AND SC.Sno=student.Sno;
    37、查询不及格的课程,并按课程号从大到小排列
        select Cno from sc where scor e <60 order by Cno ;
    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.Sno,Student.Sname from SC,Student where SC.Sno=Student.Sno and Score>80 and Cno='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.Sno=SC.Sno and SC.Cno=C.Cno and C.Tno=Teacher.Tno and Teacher.Tname='叶平' and SC.score=(select max(score)from SC where Cno=C.Cno );
    41、查询各个课程及相应的选修人数
        select count(*) from sc group by Cno;
    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.Sno,B.score from SC A  ,SC B where A.Score=B.Score and A.Cno <>B.Cno ;
    43、查询每门功成绩最好的前两名
        SELECT t1.Sno as 学生ID,t1.Cno as 课程ID,Score as 分数
          FROM SC t1
          WHERE score IN (SELECT TOP 2 score
                  FROM SC
                  WHERE t1.Cno= Cno
                ORDER BY score DESC
                  )
          ORDER BY t1.Cno;
    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  Cno as 课程号,count(*) as 人数
        from  sc 
        group  by  Cno
        order  by  count(*) desc,Cno 
    45、检索至少选修两门课程的学生学号
        select  Sno 
        from  sc 
        group  by  Sno
        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  Cno,Cname 
        from  Course 
        where  Cno  in  (select  Cno  from  sc group  by  Cno) 
    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 Sno not in (select Sno from Course,Teacher,SC where Course.Tno=Teacher.Tno and SC.Cno=course.Cno 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 Sno,avg(isnull(score,0)) from SC where Sno in (select Sno from SC where score <60 group by Sno having count(*)>2)group by Sno;
    49、检索“004”课程分数小于60,按分数降序排列的同学学号
        select Sno from SC where Cno='004'and score <60 order by score desc;

    学生表 Student(S#,Sname,Sage,Ssex)

    参考原贴:http://www.cnblogs.com/qixuejia/p/3637735.html 

    教师表 Teacher(T#,Tname)


    课程表 Course(C#,Cname,T#)

    01 表结构

      Student(Sno,Sname,Sage,Ssex)    学生表 
      Course(Cno,Cname,Tno)       课程表 
      SC(Sno,Cno,score)          成绩表 
      Teacher(Tno,Tname)        教师表


    学生成绩表 SC(S#,C#,score)

    02 建表及插入测试数据

      (1) 建表:

    新葡亰496net 1新葡亰496net 2

     1 DROP TABLE IF EXISTS student ;
     2 DROP TABLE IF EXISTS course ;
     3 DROP TABLE IF EXISTS sc ;
     4 DROP TABLE IF EXISTS teacher ;
     5 
     6 CREATE TABLE Student
     7 (
     8 Sno int,
     9 Sname varchar(32),
    10 Sage int,
    11 Ssex varchar(8)
    12 )ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
    13 
    14 CREATE TABLE Course 
    15   ( 
    16      Cno    INT, 
    17      Cname varchar(32), 
    18      Tno    INT 
    19   )ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
    20 
    21 CREATE TABLE Sc 
    22 ( 
    23 Sno    INT, 
    24 Cno   INT,
    25 score INT 
    26 )ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
    27 
    28 CREATE TABLE Teacher 
    29   ( 
    30      Tno    INT, 
    31      Tname varchar(16) 
    32   )ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
    

    View Code

      【注】MySQL数据库建表时需要添加“ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci”命令,否则中文会发生乱码。

      (2) 插入测试数据:

    新葡亰496net 3新葡亰496net 4

     1  insert into Student select 1,'刘一',18,'男' union all
     2  select 2,'钱二',19,'女' union all
     3  select 3,'张三',17,'男' union all
     4  select 4,'李四',18,'女' union all
     5  select 5,'王五',17,'男' union all
     6  select 6,'赵六',19,'女' 
     7  
     8  insert into Teacher select 1,'叶平' union all
     9  select 2,'贺高' union all
    10  select 3,'杨艳' union all
    11  select 4,'周磊';
    12  
    13  insert into Course select 1,'语文',1 union all
    14  select 2,'数学',2 union all
    15  select 3,'英语',3 union all
    16  select 4,'物理',4;
    17  
    18  insert into SC 
    19  select 1,1,56 union all 
    20  select 1,2,78 union all 
    21  select 1,3,67 union all 
    22  select 1,4,58 union all 
    23  select 2,1,79 union all 
    24  select 2,2,81 union all 
    25  select 2,3,92 union all 
    26  select 2,4,68 union all 
    27  select 3,1,91 union all 
    28  select 3,2,47 union all 
    29  select 3,3,88 union all 
    30  select 3,4,56 union all 
    31  select 4,2,88 union all 
    32  select 4,3,90 union all 
    33  select 4,4,93 union all 
    34  select 5,1,46 union all 
    35  select 5,3,78 union all 
    36  select 5,4,53 union all 
    37  select 6,1,35 union all 
    38  select 6,2,68 union all 
    39  select 6,4,71;
    

    View Code


    问题:

    03 问题及实现代码

      (1)查询“1”课程比“2”课程成绩高的所有学生的学号; 

    select a.sno from
    (select sno,score from sc where cno=1) a,
    (select sno,score from sc where cno=2) b
    where a.sno=b.sno and 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 Sno,AVG(Score) as AvgScore 
     from SC
     group by Sno
     having AVG(Score)>60
    

       (3)查询所有同学的学号、姓名、选课数、总成绩; 

     select student.sno,student.sname,count(sc.cno),sum(sc.score) from
     student left outer join sc
     on student.sno = sc.sno
     group by student.sno
     order by student.sno;
    

       (4)查询姓“李”的老师的个数; 

     select count(distinct tname) as count
     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 s.sno,s.sname 
     from student s
     where s.sno not in
     (
     select distinct(sc.sno) from sc ,course c,teacher t
     where sc.cno = c.cno and c.tno = t.tno and t.tname = '叶平'
     )
    

      (6)查询学过“1”并且也学过编号“2”课程的同学的学号、姓名;

    新葡亰496net 5

     select s.sno,s.sname from 
     student s,
     (select sno from sc where cno=1) a,
     (select sno from sc where cno=2) b
     where s.sno = a.sno and a.sno = b.sno;
    

      方法二 用exist函数

     select s.Sno,s.Sname
     from Student s,SC sc
     where s.Sno=sc.Sno and sc.Cno=1 and exists
     (
         select * from SC sc2 where sc.Sno=sc2.Sno and sc2.Cno=2
     )
    

      (7)查询学过“叶平”老师所教的所有课的同学的学号、姓名;

    新葡亰496net 6

     select s.sno,s.sname 
     from student s,teacher t,
     course c left outer join sc
     on c.cno = sc.cno 
     where t.tname="叶平" and t.tno = c.cno and s.sno = sc.sno ;
    

      或者:

     select s.sno,s.sname 
     from student s
     where s.sno in 
     (
     select sc.sno
     from sc,course c,teacher t
     where c.cno=sc.cno and c.tno=t.tno and t.tname ="叶平"
     group by sc.sno
     having count(sc.cno)=
     (
      select count(c1.cno)
      from course c1,teacher t1
      where c1.tno=t1.tno and t1,tname ="叶平"
     )
     );
    

      (8)查询课程编号“2”的成绩比课程编号“1”课程低的所有同学的学号、姓名;

    新葡亰496net 7

     select s.sno,s.sname
     from student s
     where s.sno in
     (
     select a.sno from  
     (select sno,score from sc where cno=2) a,
     (select sno,score from sc where cno=1) b
     where a.sno = b.sno and a.score < b.score
     );
    

      (9)查询有课程成绩小于60分的同学的学号、姓名;

    新葡亰496net 8

     

    select s.sno,s.sname
     from student s,sc
     where sc.score<60 and s.sno=sc.sno
     group by s.sno;
    

     

      (10)查询没有学全所有课的同学的学号、姓名;

    新葡亰496net 9

     select s.sno,s.sname
     from student s
     where s.sno not in
     (
     select sc.sno from sc
     group by sc.sno
     having count(distinct sc.cno)=
     (
      select count(distinct c.cno) from course c
     )
     );
    

      (11)查询至少有一门课与学号为“1”的同学所学相同的同学的学号和姓名;

    新葡亰496net 10

     select distinct(s.sno),s.sname 
     from student s,sc 
     where s.sno=sc.sno and sc.cno in 
     (
     select distinct(cno) from sc where sno=1
     );
    

      (12)查询至少学过学号为“1”同学所有一门课的其他同学学号和姓名;

    新葡亰496net 11

     select distinct(s.sno),s.sname 
     from student s,sc 
     where s.sno=sc.sno and s.sno != 1 and sc.cno in 
     (
     select distinct(cno) from sc where sno=1
     );
    

      (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(sc1.score) from sc sc1,course c,teacher t
     where sc1.cno = c.cno and c.tno = t.tno and t.tname="叶平"
     )
     where cno in
     (
     select cno from course c,teacher t 
     where c.tno = t.tno and t.tname="叶平"
     );
    

      (14)查询和“2”号的同学学习的课程完全相同的其他同学学号和姓名;

    新葡亰496net 12

     select s.sno,s.sname 
     from student s
     where s.sno != 2 and s.sno in
     (
     select distinct(sno) from sc
     where cno in (select cno from sc where sno=2)
     group by sno
     having count(distinct cno)=
     (
      select count(distinct cno) from sc where sno=2
     )
     );
    

      (15)删除学习“叶平”老师课的SC表记录;

    新葡亰496net 13

     delete from sc where cno in
     (
     select c.cno from course c,teacher t
     where c.tno = t.tno and t.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:①没有上过编号“2”课程的同学学号作为学号;②将“2”号课程的平均成绩作为其成绩; 

    新葡亰496net 14

     insert into sc
     select s.sno,2,(select avg(score) from sc where cno=2)
     from student s
     where s.sno not in (select distinct(sno) from sc where cno=2);
    

      (17)按平均成绩从低到高显示所有学生的“语文”、“数学”、“英语”三门的课程成绩,按如下形式显示: 学生ID,语文,数学,英语,有效课程数,有效平均分; 【此处已补回15题中被删除的数据】 

    新葡亰496net 15

     select sc0.sno as "学生ID",
     (select score from sc where sno=sc0.sno and cno =1) as "语文" ,
     (select score from sc where sno=sc0.sno and cno =2) as "数学" ,
     (select score from sc where sno=sc0.sno and cno =3) as "英语" ,
     count(sc0.cno) as "有效课程数",
     avg(sc0.score) as "有效平均分"
     from sc sc0
     group by sc0.sno
     order by avg(sc0.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; 

    新葡亰496net 16

     select cno as "课程ID",max(score) as "最高分",min(score) as "最低分"
     from sc 
     group by cno;
    

      (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;

    新葡亰496net 17

     select sc.cno as "课程ID",
     c.cname as "课程名称",
     avg(sc.score) as "平均分", 
     100*sum(case when sc.score >= 60 then 1 else 0 end)/count(sc.score) as "Percent(%)"
     from sc ,course c
     where sc.cno = c.cno
     group by sc.cno
     order by avg(sc.score) desc ;
    

      (20)查询如下课程平均成绩和及格率的百分数(备注:需要在1行内显示): 企业管理(2),OO&UML (3),数据库(4) 

    新葡亰496net 18

     select
     sum(case when cno=2 then score else 0 end)/sum(case when cno=2 then 1 else 0 end) as "企业管理平均成绩",
     100*sum(case when cno=2 and score >= 60 then 1 else 0 end)/sum(case when cno=2 then 1 else 0 end) as "企业管理及格率(%)",
     sum(case when cno=3 then score else 0 end)/sum(case when cno=3 then 1 else 0 end) as "OO&UML平均成绩",
     100*sum(case when cno=3 and score >= 60 then 1 else 0 end)/sum(case when cno=3 then 1 else 0 end) as "OO&UML及格率(%)",
     sum(case when cno=4 then score else 0 end)/sum(case when cno=4 then 1 else 0 end) as "数据库平均成绩",
     100*sum(case when cno=4 and score >= 60 then 1 else 0 end)/sum(case when cno=4 then 1 else 0 end) as "数据库及格率(%)"
     from sc;
    

      (21)查询不同老师所教不同课程平均分从高到低显示; 

    新葡亰496net 19

     select t.tname as "老师姓名",
     c.cname as "课程名称",
     avg(sc.score) as "平均分" 
     from sc,teacher t,course c
     where t.tno=c.tno and c.cno=sc.cno
     group by t.tno
     order by avg(sc.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(1),马克思(2),UML (3),数据库(4)  

    新葡亰496net 20

     select distinct 
          SC.Sno 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", 
          ifnull(T1.score,0)   ifnull(T2.score,0)   ifnull(T3.score,0)   ifnull(T4.score,0) as "总分" 
          from Student,SC  left join SC as T1 
                          on SC.Sno = T1.Sno and T1.Cno = 1
                left join SC as T2 
                          on SC.Sno = T2.Sno and T2.Cno = 2 
                left join SC as T3 
                          on SC.Sno = T3.Sno and T3.Cno = 3 
                left join SC as T4 
                          on SC.Sno = T4.Sno and T4.Cno = 4 
          where student.Sno=SC.Sno 
          order by ifnull(T1.score,0)   ifnull(T2.score,0)   ifnull(T3.score,0)   ifnull(T4.score,0) desc ; 
    

      

     

    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# = '001'
            ) a
            INNER JOIN ( SELECT *
                         FROM   dbo.SC
                         WHERE  c# = '002'
                       ) 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# = '001'
            AND EXISTS ( SELECT *
                         FROM   SC AS SC_2
                         WHERE  SC_2.S# = SC.S#
                                AND SC_2.C# = '002' )
    

     

    SQL面试笔试优质题,优秀面试题及答案。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# = '002'
                        ) score2
              FROM      Student ,
                        SC
              WHERE     Student.S# = SC.S#
                        AND C# = '001'
            ) 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# = '1001' )
    

     

    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# = '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“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# = '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;

    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# ,
                    '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(001),马克思(002),OO&UML (003),数据库(004)

    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(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# = '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、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 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#='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 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 
    

     

    新葡亰496net,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#='004'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#='001'and C#='001'; 
    

     

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