sql面試題（學生表_課程表_成績表_教師表）

時間 2019-11-07

標籤 sql 面試學生課程表成績師表欄目 SQL 简体版

原文原文鏈接

sql面試題（學生表_課程表_成績表_教師表）

原帖連接:http://bbs.csdn.net/topics/280002741html

表架構面試

Student(S#,Sname,Sage,Ssex) 學生表
Course(C#,Cname,T#) 課程表
SC(S#,C#,score) 成績表
Teacher(T#,Tname) 教師表sql

建表語句數據庫

CREATE TABLE student 
  ( 
     s#    INT, 
     sname nvarchar(32), 
     sage  INT, 
     ssex  nvarchar(8) 
  ) 

CREATE TABLE course 
  ( 
     c#    INT, 
     cname nvarchar(32), 
     t#    INT 
  ) 

CREATE TABLE sc 
  ( 
     s#    INT, 
     c#    INT, 
     score INT 
  ) 

CREATE TABLE teacher 
  ( 
     t#    INT, 
     tname nvarchar(16) 
  )

插入測試數據語句 c#

insert into Student select 1,N'劉一',18,N'男' union all
 select 2,N'錢二',19,N'女' union all
 select 3,N'張三',17,N'男' union all
 select 4,N'李四',18,N'女' union all
 select 5,N'王五',17,N'男' union all
 select 6,N'趙六',19,N'女' 
 
 insert into Teacher select 1,N'葉平' union all
 select 2,N'賀高' union all
 select 3,N'楊豔' union all
 select 4,N'周磊'
 
 insert into Course select 1,N'語文',1 union all
 select 2,N'數學',2 union all
 select 3,N'英語',3 union all
 select 4,N'物理',4
 
 insert into SC 
 select 1,1,56 union all 
 select 1,2,78 union all 
 select 1,3,67 union all 
 select 1,4,58 union all 
 select 2,1,79 union all 
 select 2,2,81 union all 
 select 2,3,92 union all 
 select 2,4,68 union all 
 select 3,1,91 union all 
 select 3,2,47 union all 
 select 3,3,88 union all 
 select 3,4,56 union all 
 select 4,2,88 union all 
 select 4,3,90 union all 
 select 4,4,93 union all 
 select 5,1,46 union all 
 select 5,3,78 union all 
 select 5,4,53 union all 
 select 6,1,35 union all 
 select 6,2,68 union all 
 select 6,4,71

問題網絡

問題： 
1、查詢「001」課程比「002」課程成績高的全部學生的學號； 
  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分的同窗的學號和平均成績； 
    select S#,avg(score) 
    from sc 
    group by S# having avg(score) >60; 
3、查詢全部同窗的學號、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」老師課的同窗的學號、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」而且也學過編號「002」課程的同窗的學號、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」老師所教的全部課的同窗的學號、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」課程低的全部同窗的學號、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、查詢全部課程成績小於60分的同窗的學號、姓名； 
  select S#,Sname 
  from Student 
  where S# not in (select S.S# from Student AS S,SC where S.S#=SC.S# and score>60); 
10、查詢沒有學全全部課的同窗的學號、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爲「1001」的同窗所學相同的同窗的學號和姓名； 
    select distinct S#,Sname from Student,SC where Student.S#=SC.S# and SC.C# in (select C# from SC where S#='1001'); 
12、查詢至少學過學號爲「001」同窗全部一門課的其餘同窗學號和姓名； 
    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成此課程的平均成績； 
    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」號的同窗學習的課程徹底相同的其餘同窗學號和姓名； 
    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，這些記錄要求符合如下條件：沒有上過編號「003」課程的同窗學號、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全部學生的「數據庫」、「企業管理」、「英語」三門的課程成績，按以下形式顯示： 學生ID,,數據庫,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 數據庫 
        ,(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：以以下形式顯示：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# 
                    ); 
本身寫的:select c# ,max(score)as 最高分 ,min(score) as 最低分 from dbo.sc  group by 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、查詢以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），數據庫（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 數據庫平均分 
        ,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 數據庫及格百分數 
  FROM SC

21、查詢不一樣老師所教不一樣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、查詢以下課程成績第 3 名到第 6 名的學生成績單：企業管理（001），馬克思（002），UML （003），數據庫（004） 
    [學生ID],[學生姓名],企業管理,馬克思,UML,數據庫,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 數據庫, 
      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、查詢學平生均成績及其名次 
      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:(不考慮成績並列狀況) 
      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所有學生的學號和姓名 
  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(注：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的全部學生的學號、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、查詢課程名稱爲「數據庫」，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='數據庫'and score <60; 
35、查詢全部學生的選課狀況； 
    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、查詢課程編號爲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、查詢不一樣課程成績相同的學生的學號、課程號、學生成績 
  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、查詢所有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窗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窗學號 
    select S# from SC where C#='004'and score <60 order by score desc; 
50、刪除「002」同窗的「001」課程的成績 
delete from Sc where S#='001'and C#='001';

問題描述：架構

本題用到下面三個關係表：post

CARD 借書卡。 CNO 卡號，NAME 姓名，CLASS 班級學習

BOOKS 圖書。 BNO 書號，BNAME 書名,AUTHOR 做者，PRICE 單價，QUANTITY 庫存冊數測試

BORROW 借書記錄。 CNO 借書卡號，BNO 書號，RDATE 還書日期

備註：限定每人每種書只能借一本；庫存冊數隨借書、還書而改變。

要求實現以下15個處理：

1. 寫出創建BORROW表的SQL語句，要求定義主碼完整性約束和引用完整性約束
--實現代碼：
CREATE TABLE BORROW(
    CNO int FOREIGN KEY REFERENCES CARD(CNO),
    BNO int FOREIGN KEY REFERENCES BOOKS(BNO),
    RDATE datetime,
    PRIMARY KEY(CNO,BNO)) 

2. 找出借書超過5本的讀者,輸出借書卡號及所借圖書冊數
--實現代碼：
SELECT CNO,借圖書冊數=COUNT(*)
FROM BORROW
GROUP BY CNO
HAVING COUNT(*)>5

3. 查詢借閱了"水滸"一書的讀者，輸出姓名及班級
--實現代碼：
SELECT * FROM CARD c
WHERE EXISTS(
    SELECT * FROM BORROW a,BOOKS b 
    WHERE a.BNO=b.BNO
        AND b.BNAME=N'水滸'
        AND a.CNO=c.CNO) 

4. 查詢過時未還圖書，輸出借閱者（卡號）、書號及還書日期
--實現代碼：
SELECT * FROM BORROW 
WHERE RDATE<GETDATE() 

5. 查詢書名包括"網絡"關鍵詞的圖書，輸出書號、書名、做者
--實現代碼：
SELECT BNO,BNAME,AUTHOR FROM BOOKS
WHERE BNAME LIKE N'%網絡%' 

6. 查詢現有圖書中價格最高的圖書，輸出書名及做者
--實現代碼：
SELECT BNO,BNAME,AUTHOR FROM BOOKS
WHERE PRICE=(
    SELECT MAX(PRICE) FROM BOOKS) 

7. 查詢當前借了"計算方法"但沒有借"計算方法習題集"的讀者，輸出其借書卡號，並按卡號降序排序輸出
--實現代碼：
SELECT a.CNO
FROM BORROW a,BOOKS b
WHERE a.BNO=b.BNO AND b.BNAME=N'計算方法'
    AND NOT EXISTS(
        SELECT * FROM BORROW aa,BOOKS bb
        WHERE aa.BNO=bb.BNO
            AND bb.BNAME=N'計算方法習題集'
            AND aa.CNO=a.CNO)
ORDER BY a.CNO DESC 

8. 將"C01"班同窗所借圖書的還期都延長一週
--實現代碼：
UPDATE b SET RDATE=DATEADD(Day,7,b.RDATE)
FROM CARD a,BORROW b
WHERE a.CNO=b.CNO
    AND a.CLASS=N'C01' 

9. 從BOOKS表中刪除當前無人借閱的圖書記錄
--實現代碼：
DELETE A FROM BOOKS a
WHERE NOT EXISTS(
    SELECT * FROM BORROW
    WHERE BNO=a.BNO) 

10. 若是常常按書名查詢圖書信息，請創建合適的索引
--實現代碼：
CREATE CLUSTERED INDEX IDX_BOOKS_BNAME ON BOOKS(BNAME)

11. 在BORROW表上創建一個觸發器，完成以下功能：若是讀者借閱的書名是"數據庫技術及應用"，就將該讀者的借閱記錄保存在BORROW_SAVE表中（注ORROW_SAVE表結構同BORROW表）
--實現代碼：
CREATE TRIGGER TR_SAVE ON BORROW
FOR INSERT,UPDATE
AS
IF @@ROWCOUNT>0
INSERT BORROW_SAVE SELECT i.*
FROM INSERTED i,BOOKS b
WHERE i.BNO=b.BNO
    AND b.BNAME=N'數據庫技術及應用' 

12. 創建一個視圖，顯示"力01"班學生的借書信息（只要求顯示姓名和書名）
--實現代碼：
CREATE VIEW V_VIEW
AS
SELECT a.NAME,b.BNAME
FROM BORROW ab,CARD a,BOOKS b
WHERE ab.CNO=a.CNO
    AND ab.BNO=b.BNO
    AND a.CLASS=N'力01'

13. 查詢當前同時借有"計算方法"和"組合數學"兩本書的讀者，輸出其借書卡號，並按卡號升序排序輸出
--實現代碼：
SELECT a.CNO
FROM BORROW a,BOOKS b
WHERE a.BNO=b.BNO
    AND b.BNAME IN(N'計算方法',N'組合數學')
GROUP BY a.CNO
HAVING COUNT(*)=2
ORDER BY a.CNO DESC 

14. 假定在建BOOKS表時沒有定義主碼，寫出爲BOOKS表追加定義主碼的語句
--實現代碼：
ALTER TABLE BOOKS ADD PRIMARY KEY(BNO) 

15.1 將NAME最大列寬增長到10個字符（假定原爲6個字符）
--實現代碼：
ALTER TABLE CARD ALTER COLUMN NAME varchar(10) 

15.2 爲該表增長1列NAME（系名），可變長，最大20個字符
--實現代碼：
ALTER TABLE CARD ADD 系名 varchar(20)

問題描述：爲管理崗位業務培訓信息，創建3個表:

S (S#,SN,SD,SA) S#,SN,SD,SA 分別表明學號、學員姓名、所屬單位、學員年齡

C (C#,CN ) C#,CN 分別表明課程編號、課程名稱

SC ( S#,C#,G ) S#,C#,G 分別表明學號、所選修的課程編號、學習成績

要求實現以下5個處理：

1. 使用標準SQL嵌套語句查詢選修課程名稱爲’稅收基礎’的學員學號和姓名 
--實現代碼：
SELECT SN,SD FROM S
WHERE [S#] IN(
    SELECT [S#] FROM C,SC
    WHERE C.[C#]=SC.[C#]
        AND CN=N'稅收基礎')


2. 使用標準SQL嵌套語句查詢選修課程編號爲’C2’的學員姓名和所屬單位
--實現代碼：
SELECT S.SN,S.SD FROM S,SC
WHERE S.[S#]=SC.[S#]
    AND SC.[C#]='C2'

3. 使用標準SQL嵌套語句查詢不選修課程編號爲’C5’的學員姓名和所屬單位
--實現代碼：
SELECT SN,SD FROM S
WHERE [S#] NOT IN(
    SELECT [S#] FROM SC 
    WHERE [C#]='C5')

4. 使用標準SQL嵌套語句查詢選修所有課程的學員姓名和所屬單位
--實現代碼：
SELECT SN,SD FROM S
WHERE [S#] IN(
    SELECT [S#] FROM SC 
        RIGHT JOIN C ON SC.[C#]=C.[C#]
    GROUP BY [S#]
    HAVING COUNT(*)=COUNT(DISTINCT [S#]))

5. 查詢選修了課程的學員人數
--實現代碼：
SELECT 學員人數=COUNT(DISTINCT [S#]) FROM SC

6. 查詢選修課程超過5門的學員學號和所屬單位
--實現代碼：
SELECT SN,SD FROM S
WHERE [S#] IN(
    SELECT [S#] FROM SC 
    GROUP BY [S#]
    HAVING COUNT(DISTINCT [C#])>5)