oracle面试题1

1、题目要求

已知关系模式：
S (SNO,SNAME）学生关系。SNO 为学号，SNAME 为姓名
C (CNO,CNAME,CTEACHER)课程关系。CNO 为课程号，CNAME 为课程名，CTEACHER 为任课教师
SC(SNO,CNO,SCGRADE) 选课关系。SCGRADE 为成绩

• 1.找出没有选修过“刘备”老师讲授课程的所有学生姓名
• 2.列出有二门以上（含两门）不及格课程的学生姓名及其平均成绩
• 3.列出既学过“c001”号课程，又学过“c002”号课程的所有学生姓名
• 4.列出“c001”号课成绩比“s002”号同学该门课成绩高的所有学生的学号
• 5.列出“c001”号课成绩比“c002”号课成绩高的所有学生的学号及其“1”号课和“2”号课的成绩

2、建表语句

create table C
(
  cno      ),
  cname    ),
  cteacher )
)
;
comment on column C.cno
  is '课程号';
comment on column C.cname
  is '课程名';
comment on column C.cteacher
  is '任课教师';

create table S
(
  sno   ),
  sname )
)
;
comment on column S.sno
  is '学号';
comment on column S.sname
  is '姓名';

create table SC
(
  sno     ),
  cno     ),
  scgrade )
)
;
comment on column SC.scgrade
  is '成绩';

insert into C (cno, cname, cteacher)
values ('c001', '语文', '刘备');
insert into C (cno, cname, cteacher)
values ('c002', '数学', '关于');
insert into C (cno, cname, cteacher)
values ('c003', '英语', '张飞');
commit;

insert into S (sno, sname)
values ('s001', '小红');
insert into S (sno, sname)
values ('s002', '小明');
insert into S (sno, sname)
values ('s003', '小庄');
commit;

insert into SC (sno, cno, scgrade)
');
insert into SC (sno, cno, scgrade)
');
insert into SC (sno, cno, scgrade)
');
insert into SC (sno, cno, scgrade)
');
insert into SC (sno, cno, scgrade)
');
insert into SC (sno, cno, scgrade)
');
insert into SC (sno, cno, scgrade)
');
insert into SC (sno, cno, scgrade)
');
commit;

3、参考答案

--1.找出没有选修过“刘备”老师讲授课程的所有学生姓名
select sname
  from s
 where not exists (select *
          from sc, c
         where sc.cno = c.cno
           and c.cteacher = '刘备'
           and sc.sno = s.sno)

--2.列出有二门以上（含两门）不及格课程的学生姓名及其平均成绩
select s.sno, s.sname, Avg(sc.scgrade)
  from sc,
       s,
       (select sc.sno
          from sc

         group by sno
        ) A
 where sc.sno = A.sno
   and s.sno = A.sno
 group by s.sno, s.sname

--3.列出既学过“c001”号课程，又学过“c002”号课程的所有学生姓名
select *
  from s,
       (select sc.sno
          from sc, c
         where sc.cno = c.cno
           and c.cno in ('c001', 'c002')
         group by sc.sno
        ) A
 where s.sno = A.sno

--4.列出“c001”号课成绩比“s002”号同学该门课成绩高的所有学生的学号
select s.sno
  from s, sc sc1, sc sc2
 where sc1.cno = 'c001'
   and sc2.sno = 's002'
   and s.sno = sc1.sno
   and sc1.cno = sc2.cno
   and sc1.scgrade > sc2.scgrade

--5.列出“c001”号课成绩比“c002”号课成绩高的所有学生的学号及其“1”号课和“2”号课的成绩
select sc1.sno, sc1.scgrade, sc2.scgrade
  from sc sc1, sc sc2
 where sc1.cno = 'c001'
   and sc2.cno = 'c002'
   and sc1.sno = sc2.sno
   and sc1.scgrade > sc2.scgrade