数据库基本操作-MySQL 튜토리얼-php.cn

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데이터 베이스

MySQL 튜토리얼

数据库基本操作

Jun 07, 2016 pm 03:59 PM

sag student 기본 조작 데이터 베이스 데이터 시트

一、数据表 Student(S#,Sname,Sage,Ssex) 学生表 S#：学号；Sname：学生姓名；Sage：学生年龄；Ssex：学生性别 Course(C#,Cname,T#) 课程表 C#,课程编号；Cname：课程名字；T#：教师编号 SC(S#,C#,score) 成绩表 S#：学号；C#,课程编号；score：成绩 Teacher(

一、数据表 Student(S#,Sname,Sage,Ssex) 学生表 S#：学号；Sname：学生姓名；Sage：学生年龄；Ssex：学生性别
Course(C#,Cname,T#) 课程表 C#,课程编号；Cname：课程名字；T#：教师编号
SC(S#,C#,score) 成绩表 S#：学号；C#,课程编号；score：成绩
Teacher(T#,Tname) 教师表 T#：教师编号； Tname：教师名字

二、基本操作：
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 s#,score from SC where C#=&#39;001&#39;) a,(select s#,score
      from SC where C#=&#39;002&#39;) b
      where a.score>b.score and a.s#=b.s#;

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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 sc
      group by S# having avg(score) >60;

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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

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4、查询姓“李”的老师的个数；

      select count(distinct(Tname))
      from Teacher
      where Tname like &#39;李%&#39;;

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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=&#39;叶平&#39;);

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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#=&#39;001&#39;and exists( Select * from SC as SC_2 where SC_2.S#=SC.S# and SC_2.C#=&#39;002&#39;);

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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=&#39;叶平&#39; group by S# having count(SC.C#)=(select count(C#) from Course,Teacher  where Teacher.T#=Course.T# and Tname=&#39;叶平&#39;));

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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#=&#39;002&#39;) score2
      from Student,SC where Student.S#=SC.S# and C#=&#39;001&#39;) S_2 where score2 <score;

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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 S.S#=SC.S# and score>60);

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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);

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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#=&#39;1001&#39;;

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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#=&#39;001&#39;);

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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=&#39;叶平&#39;);

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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#=&#39;1002&#39;)
       group by S# having count(*)=(select count(*) from SC where S#=&#39;1002&#39;);

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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=&#39;叶平&#39;;

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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#,&#39;002&#39;,(Select avg(score)
       from SC where C#=&#39;002&#39;) from Student where S# not in (Select S# from SC where C#=&#39;002&#39;);

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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#=&#39;004&#39;) AS 数据库
           ,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#=&#39;001&#39;) AS 企业管理
           ,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#=&#39;006&#39;) 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)

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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#
                    );

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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

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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# =&#39;001&#39; THEN score ELSE 0 END)/SUM(CASE C# WHEN &#39;001&#39; THEN 1 ELSE 0 END) AS 企业管理平均分
            ,100 * SUM(CASE WHEN C# = &#39;001&#39; AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = &#39;001&#39; THEN 1 ELSE 0 END) AS 企业管理及格百分数
            ,SUM(CASE WHEN C# = &#39;002&#39; THEN score ELSE 0 END)/SUM(CASE C# WHEN &#39;002&#39; THEN 1 ELSE 0 END) AS 马克思平均分
            ,100 * SUM(CASE WHEN C# = &#39;002&#39; AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = &#39;002&#39; THEN 1 ELSE 0 END) AS 马克思及格百分数
            ,SUM(CASE WHEN C# = &#39;003&#39; THEN score ELSE 0 END)/SUM(CASE C# WHEN &#39;003&#39; THEN 1 ELSE 0 END) AS UML平均分
            ,100 * SUM(CASE WHEN C# = &#39;003&#39; AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = &#39;003&#39; THEN 1 ELSE 0 END) AS UML及格百分数
            ,SUM(CASE WHEN C# = &#39;004&#39; THEN score ELSE 0 END)/SUM(CASE C# WHEN &#39;004&#39; THEN 1 ELSE 0 END) AS 数据库平均分
            ,100 * SUM(CASE WHEN C# = &#39;004&#39; AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = &#39;004&#39; THEN 1 ELSE 0 END) AS 数据库及格百分数
      FROM SC

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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

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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# = &#39;001&#39;
            LEFT JOIN SC AS T2
                      ON SC.S# = T2.S# AND T2.C# = &#39;002&#39;
            LEFT JOIN SC AS T3
                      ON SC.S# = T3.S# AND T3.C# = &#39;003&#39;
            LEFT JOIN SC AS T4
                      ON SC.S# = T4.S# AND T4.C# = &#39;004&#39;
      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# = &#39;k1&#39;
            LEFT JOIN sc AS T2
                      ON sc.S# = T2.S# AND T2.C# = &#39;k2&#39;
            LEFT JOIN sc AS T3
                      ON sc.S# = T3.S# AND T3.C# = &#39;k3&#39;
            LEFT JOIN sc AS T4
                      ON sc.S# = T4.S# AND T4.C# = &#39;k4&#39;
      ORDER BY ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) DESC);

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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;

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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;

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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#;

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26、查询每门课程被选修的学生数

       select c#,count(S#) from sc group by C#;

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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;

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28、查询男生、女生人数

      Select count(Ssex) as 男生人数 from Student group by Ssex having Ssex=&#39;男&#39;;
      Select count(Ssex) as 女生人数 from Student group by Ssex having Ssex=&#39;女&#39;;

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29、查询姓“张”的学生名单

      SELECT Sname FROM Student WHERE Sname like &#39;张%&#39;;

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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;;

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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))=&#39;1981&#39;;

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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 ;

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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;

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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=&#39;数据库&#39;and score <60;

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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# ;

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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#;

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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# ;

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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;003&#39;;

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39、求选了课程的学生人数

      select count(*) from sc;

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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=&#39;叶平&#39; and SC.score=(select max(score)from SC where C#=C.C# );

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41、查询各个课程及相应的选修人数

      select count(*) from sc group by C#;

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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# ;

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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#;

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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#

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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

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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#)

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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=&#39;叶平&#39;);

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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#;

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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#=&#39;004&#39;and score <60 order by score desc;

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50、删除“002”同学的“001”课程的成绩

      delete from Sc where S#=&#39;002&#39;and C#=&#39;001&#39;;

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