SQL面试题及答案

我觉得里面有些答案是不正确的，请只作参考

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

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.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; 
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 
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.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'); 
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 S.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； 
    Delect 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 scor e <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 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 
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#='002'and C#='001';

建表语句

1. -- Create table
2. create table DB_IMP_COURSE
3. (
4. C#    NUMBER,
5. CNAME VARCHAR2(10),
6. T#    NUMBER
7. )
8. tablespace SYSTEM
9. pctfree 10
10. pctused 40
11. initrans 1
12. maxtrans 255
13. storage
14. (
15. initial 64K
16. minextents 1
17. maxextents unlimited
18. );
19. -- Add comments to the table
20. comment on table DB_IMP_COURSE
21. is '课程表';
22. -- Add comments to the columns
23. comment on column DB_IMP_COURSE.C#
24. is '课程编号';
25. comment on column DB_IMP_COURSE.CNAME
26. is '课程名字';
27. comment on column DB_IMP_COURSE.T#
28. is '教师编号';

1. -- Create table
2. create table DB_IMP_SC
3. (
4. S#    NUMBER not null,
5. C#    NUMBER,
6. SCORE VARCHAR2(10)
7. )
8. tablespace SYSTEM
9. pctfree 10
10. pctused 40
11. initrans 1
12. maxtrans 255
13. storage
14. (
15. initial 64K
16. minextents 1
17. maxextents unlimited
18. );
19. -- Add comments to the table
20. comment on table DB_IMP_SC
21. is ' 成绩表 ';
22. -- Add comments to the columns
23. comment on column DB_IMP_SC.S#
24. is '学号';
25. comment on column DB_IMP_SC.C#
26. is '课程编号';
27. comment on column DB_IMP_SC.SCORE
28. is '成绩';

1. -- Create table
2. create table DB_IMP_STUDENT
3. (
4. S#    NUMBER not null,
5. SNAME VARCHAR2(12),
6. SAGE  VARCHAR2(3),
7. SSEX  VARCHAR2(2)
8. )
9. tablespace SYSTEM
10. pctfree 10
11. pctused 40
12. initrans 1
13. maxtrans 255
14. storage
15. (
16. initial 64K
17. minextents 1
18. maxextents unlimited
19. );
20. -- Add comments to the table
21. comment on table DB_IMP_STUDENT
22. is ' 学生表';
23. -- Add comments to the columns
24. comment on column DB_IMP_STUDENT.S#
25. is '学号';
26. comment on column DB_IMP_STUDENT.SNAME
27. is '学生姓名';
28. comment on column DB_IMP_STUDENT.SAGE
29. is '学生年龄';
30. comment on column DB_IMP_STUDENT.SSEX
31. is '学生性别
32. ';

1. -- Create table
2. create table DB_IMP_TEACHER
3. (
4. T#    NUMBER not null,
5. TNAME VARCHAR2(12)
6. )
7. tablespace SYSTEM
8. pctfree 10
9. pctused 40
10. initrans 1
11. maxtrans 255
12. storage
13. (
14. initial 64K
15. minextents 1
16. maxextents unlimited
17. );
18. -- Add comments to the table
19. comment on table DB_IMP_TEACHER
20. is '教师表 ';
21. -- Add comments to the columns
22. comment on column DB_IMP_TEACHER.T#
23. is '教师编号';
24. comment on column DB_IMP_TEACHER.TNAME
25. is '教师名字';