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Jun 07, 2016 pm 03:59 PM

sag student Basic operations database data sheet

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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Analysis of the basic principles of the MySQL database management system MySQL is a commonly used relational database management system that uses structured query language (SQL) for data storage and management. This article will introduce the basic principles of the MySQL database management system, including database creation, data table design, data addition, deletion, modification, and other operations, and provide specific code examples. 1. Database Creation In MySQL, you first need to create a database instance to store data. The following code can create a file named "my

Tips and practices for handling Chinese garbled characters in databases with PHP Mar 27, 2024 pm 05:21 PM

PHP is a back-end programming language widely used in website development. It has powerful database operation functions and is often used to interact with databases such as MySQL. However, due to the complexity of Chinese character encoding, problems often arise when dealing with Chinese garbled characters in the database. This article will introduce the skills and practices of PHP in handling Chinese garbled characters in databases, including common causes of garbled characters, solutions and specific code examples. Common reasons for garbled characters are incorrect database character set settings: the correct character set needs to be selected when creating the database, such as utf8 or u

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