資料庫基本操作，資料庫

資料庫基本操作，資料庫
一、資料表Student(S#,Sname,Sage,Ssex) 學生表   S#：學號；Sname：學生姓名；Sage：學生年齡；Ssex：學生性別
Course(C#,Cname,T#) 課程表           C#,課程編號；Cname：課程名字；T#：教師編號
SC(S#,C#,score) 成績表               S#：學號；C#,課程編號；score：成績
Teacher(T#,Tname) 教師表             T#：教師編號； Tname：教師名字

二、基本操作：
   1、查詢“001”課程比“002”課程成績高的所有學生的學號；

      select a.S# from (select s#,score from SC where C#='001') a,(select s#,score      from SC where C#='002') b      where a.score>b.score and a.s#=b.s#;

   2、查詢平均成績大於60分的同學的學號和平均成績；

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

   3、查詢所有同學的學號、姓名、選課數、總成績；

      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

   4、查詢姓“李”的老師的個數；

      select count(distinct(Tname))      from Teacher      where Tname like '李%';

   5、查詢沒學過“葉平”老師課的同學的學號、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='葉平');

   6、查詢學過“001”並且也學過編號“002”課程的同學的學號、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');

   7、查詢學過“葉平”老師所教的所有課的同學的學號、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='葉平' group by S# having count(SC.C#)=(select count(C#) from Course,Teacher  where Teacher.T#=Course.T# and Tname='葉平'));

   8、查詢課程編號“002”的成績比課程編號“001”課程低的所有同學的學號、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、查詢所有課程成績小於60分的同學的學號、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);

   10、查詢沒有學全所有課的同學的學號、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、查詢至少有一門課與學號為“1001”的同學所學相同的同學的學號和姓名；

       select S#,Sname from Student,SC where Student.S#=SC.S# and C# in select C# from SC where S#='1001';

   12、查詢至少學過學號為“001”同學所有一門課的其他同學學號和姓名；

       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“葉平”老師教的課的成績都更改為此課程的平均成績； 

       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='葉平');

   14、查詢和“1002”號的同學學習的課程完全相同的其他同學學號和姓名；

       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、刪除學習“葉平”老師課的SC表記錄；

       Delect SC       from course ,Teacher        where Course.C#=SC.C# and Course.T#= Teacher.T# and Tname='葉平';

   16、向SC表中插入一些記錄，這些記錄要求符合以下條件：沒有上過編號“003”課程的同學學號、2、號課的平均成績；

       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、按平均成績從高到低顯示所有學生的“資料庫”、“企業管理”、“英語”三門的課程成績，按如下形式顯示： 學生ID,,資料庫,企業管理,英語,        有效課程數,有效平均分

        SELECT S# as 學生ID           ,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#='004') AS 資料庫           ,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#='001') AS 企業管理           ,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#='006') AS 英語           ,COUNT(*) AS 有效課程數, AVG(t.score) AS 平均成績        FROM SC AS t        GROUP BY S#        ORDER BY avg(t.score) 

   18、查詢各科成績最高和最低的分：以如下形式顯示：課程ID，最高分，最低分

       SELECT L.C# As 課程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、按各科平均成績從低到高和及格率的百分數從高到低順序

        SELECT t.C# AS 課程號,max(course.Cname)AS 課程名,isnull(AVG(score),0) AS 平均成績           ,100 * SUM(CASE WHEN  isnull(score,0)>=60 THEN 1 ELSE 0 END)/COUNT(*) AS 及格百分數        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、查詢如下課程平均成績和及格率的百分數(用"1行"顯示): 企業管理（001），馬克思（002），OO&UML （003），資料庫（004）

       SELECT SUM(CASE WHEN C# ='001' THEN score ELSE 0 END)/SUM(CASE C# WHEN '001' THEN 1 ELSE 0 END) AS 企業管理平均分            ,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 企業管理及格百分數            ,SUM(CASE WHEN C# = '002' THEN score ELSE 0 END)/SUM(CASE C# WHEN '002' THEN 1 ELSE 0 END) AS 馬克思平均分            ,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 馬克思及格百分數            ,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及格百分數            ,SUM(CASE WHEN C# = '004' THEN score ELSE 0 END)/SUM(CASE C# WHEN '004' THEN 1 ELSE 0 END) AS 資料庫平均分            ,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 資料庫及格百分數      FROM SC

   21、查詢不同老師所教不同課程平均分從高到低顯示

       SELECT max(Z.T#) AS 教師ID,MAX(Z.Tname) AS 教師姓名,C.C# AS 課程ＩＤ,MAX(C.Cname) AS 課程名稱,AVG(Score) AS 平均成績       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、查詢如下課程成績第 3 名到第 6 名的學產生績單：企業管理（001），馬克思（002），UML （003），資料庫（004）
      [學生ID],[學生姓名],企業管理,馬克思,UML,資料庫,平均成績

     SELECT  DISTINCT top 3      SC.S# As 學生學號,        Student.Sname AS 學生姓名 ,      T1.score AS 企業管理,      T2.score AS 馬克思,      T3.score AS UML,      T4.score AS 資料庫,      ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) as 總分      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、統計列印各科成績,各分數段人數:課程ID,課程名稱,[100-85],[85-70],[70-60],[ <60]

       SELECT SC.C# as 課程ID, Cname as 課程名稱        ,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、查詢學生平均成績及其名次     

       SELECT 1+(SELECT COUNT( distinct 平均成績)              FROM (SELECT S#,AVG(score) AS 平均成績                      FROM SC                  GROUP BY S#                  ) AS T1            WHERE 平均成績 > T2.平均成績) as 名次,         S# as 學生學號,平均成績        FROM (SELECT S#,AVG(score) 平均成績               FROM SC            GROUP BY S#              ) AS T2        ORDER BY 平均成績 desc;

   25、查詢各科成績前三名的記錄:(不考慮成績並列情況)

      SELECT t1.S# as 學生ID,t1.C# as 課程ID,Score as 分數      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、查詢每門課程被選修的學生數

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

   27、查詢出只選修了一門課程的全部學生的學號和姓名

      select SC.S#,Student.Sname,count(C#) AS 選課數      from SC ,Student      where SC.S#=Student.S# group by SC.S# ,Student.Sname having count(C#)=1;

   28、查詢男生、女生人數

      Select count(Ssex) as 男生人數 from Student group by Ssex having Ssex='男';      Select count(Ssex) as 女生人數 from Student group by Ssex having Ssex='女';

   29、查詢姓“張”的學生名單

      SELECT Sname FROM Student WHERE Sname like '張%';

   30、查詢同名同性學生名單，並統計同名人數

      select Sname,count(*) from Student group by Sname having  count(*)>1;;

   31、1981年出生的學生名單(註：Student表中Sage列的類型是datetime)

      select Sname,  CONVERT(char (11),DATEPART(year,Sage)) as age      from student      where  CONVERT(char(11),DATEPART(year,Sage))='1981';

   32、查詢每門課程的平均成績，結果按平均成績升序排列，平均成績相同時，按課程號降序排列

       Select C#,Avg(score) from SC group by C# order by Avg(score),C# DESC ;

   33、查詢平均成績大於85的所有學生的學號、姓名和平均成績

      select Sname,SC.S# ,avg(score)      from Student,SC      where Student.S#=SC.S# group by SC.S#,Sname having    avg(score)>85;

   34、查詢課程名稱為“資料庫”，且分數低於60的學生姓名和分數

      Select Sname,isnull(score,0)      from Student,SC,Course      where SC.S#=Student.S# and SC.C#=Course.C# and  Course.Cname='資料庫'and score <60;

   35、查詢所有學生的選課情況；

      SELECT SC.S#,SC.C#,Sname,Cname      FROM SC,Student,Course      where SC.S#=Student.S# and SC.C#=Course.C# ;

   36、查詢任何一門課程成績在70分以上的姓名、課程名稱和分數；

      SELECT  distinct student.S#,student.Sname,SC.C#,SC.score      FROM student,Sc      WHERE SC.score>=70 AND SC.S#=student.S#;

   37、查詢不及格的課程，並按課程號從大到小排列

      select c# from sc where scor e <60 order by C# ;

   38、查詢課程編號為003且課程成績在80分以上的學生的學號和姓名；

      select SC.S#,Student.Sname from SC,Student where SC.S#=Student.S# and Score>80 and C#='003';

   39、求選了課程的學生人數

      select count(*) from sc;

   40、查詢選修“葉平”老師所授課程的學生中，成績最高的學生姓名及其成績

      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='葉平' and SC.score=(select max(score)from SC where C#=C.C# );

   41、查詢各個課程及相應的選修人數

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

   42、查詢不同課程成績相同的學生的學號、課程號、學產生績

      select distinct  A.S#,B.score from SC A  ,SC B where A.Score=B.Score and A.C# <>B.C# ;

   43、查詢每門功成績最好的前兩名

      SELECT t1.S# as 學生ID,t1.C# as 課程ID,Score as 分數        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、統計每門課程的學生選修人數（超過10人的課程才統計）。要求輸出課程號和選修人數，查詢結果按人數降序排列，查詢結果按人數降序排

       列，若人數相同，按課程號升序排列 

       select  C# as 課程號,count(*) as 人數       from  sc        group  by  C#       order  by  count(*) desc,c# 

   45、檢索至少選修兩門課程的學生學號

      select  S#       from  sc       group  by  s#      having  count(*)  >  =  2

   46、查詢全部學生都選修的課程的課程號和課程名

      select  C#,Cname       from  Course       where  C#  in  (select  c#  from  sc group  by  c#) 

   47、查詢沒學過“葉平”老師講授的任一門課程的學生姓名

      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='葉平');

   48、查詢兩門以上不及格課程的同學的學號及其平均成績

      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、檢索“004”課程分數小於60，按分數降序排列的同學學號

      select S# from SC where C#='004'and score <60 order by score desc;

   50、刪除“002”同學的“001”課程的成績

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

sql資料庫的基本操作

命令列
1、顯示當前資料庫伺服器中的資料庫列表：mysql> SHOW DATABASES;
2、建立資料庫：mysql> CREATE DATABASE 庫名;
3、建立資料表：mysql> USE 庫名;mysql> CREATE TABLE 表名 (欄位名 VARCHAR(20), 欄位名 CHAR(1));
4、刪除資料庫：mysql> DROP DATABASE 庫名;
5、刪除資料表：mysql> DROP TABLE 表名；
6、將表中記錄清空：mysql> DELETE FROM 表名;
7、往表中插入記錄：mysql> INSERT INTO 表名 VALUES ("hyq","M");
8、更新表中資料：mysql-> UPDATE 表名 SET 欄位名1='a',欄位名2='b' WHERE 欄位名3='c';
9、用文本方式將資料裝入資料表中：mysql> load data local infile "d:/mysql.txt" into table 表名;
10、匯入.sql檔案命令：mysql> USE 資料庫名;mysql> source d:/mysql.sql;
11、命令列修改root密碼：mysql> update mysql.user set password=password('新密碼') where user='root';mysql> flush privileges;
12.修改密碼的三種方法:mysql>update user set password=password('123456') where user='joy_pen';mysql>flush privileges;mysql>set password for 'joy_oen'=password('123456');mysql>grant usage on *.* to 'joy_pen' identified by '123456';
1、建立資料庫
命令：create database <資料庫名>例如：建立一個名為xhkdb的資料庫mysql> create database xhkdb;
2、顯示所有的資料庫
命令：show databases （注意：最後有個s）mysql> show databases;
3、刪除資料庫
命令：drop database <資料庫名>例如：刪除名為 xhkdb的資料庫mysql> drop database xhkdb;
4、串連資料庫
命令： use <資料庫名>例如：如果xhkdb資料庫存在，嘗試存取它：mysql> use xhkdb;工具提示：Database changed
5、當前選擇（串連）的資料庫mysql> select database();
6、當前資料庫包含的表資訊：mysql> show tables; （注意：最後有個s）
三、表操作，操作之前應串連某個資料庫
1、建表
命令：create table <表名......餘下全文>>
 
基本要 可以夠完成對資料庫的基本操作；包括建立資料庫，實現對資料庫裡面的表的添加，刪除；以及可以夠完成

不同的公司用的開發平台不一樣，側重點也不一樣，所以不能一概而論。 個人認為要達到對資料庫的開發的和代碼的設計能力 中能看的著，但摸不著