创建学生表，成绩表，教师表，课程表，分别添加数据信息
create table student(
sno varchar2(10) primary key,
sname varchar2(20),
sage number(2),
ssex varchar2(5)
);
create table teacher(
tno varchar2(10) primary key,
tname varchar2(20)
);
create table course(
cno varchar2(10),
cname varchar2(20),
tno varchar2(20),
constraint pk_course primary key (cno,tno)
);
create table sc(
sno varchar2(10),
cno varchar2(10),
score number(4,2),
constraint pk_sc primary key (sno,cno)
);
/*******初始化学生表的数据******/
insert into student values ('s001','张三',23,'男');
insert into student values ('s002','李四',23,'男');
insert into student values ('s003','吴鹏',25,'男');
insert into student values ('s004','琴沁',20,'女');
insert into student values ('s005','王丽',20,'女');
insert into student values ('s006','李波',21,'男');
insert into student values ('s007','刘玉',21,'男');
insert into student values ('s008','萧蓉',21,'女');
insert into student values ('s009','陈萧晓',23,'女');
insert into student values ('s010','陈美',22,'女');
commit;
/******************初始化教师表***********************/
insert into teacher values ('t001', '刘阳');
insert into teacher values ('t002', '谌燕');
insert into teacher values ('t003', '胡明星');
commit;
/***************初始化课程表****************************/
insert into course values ('c001','J2SE','t002');
insert into course values ('c002','Java Web','t002');
insert into course values ('c003','SSH','t001');
insert into course values ('c004','Oracle','t001');
insert into course values ('c005','SQL SERVER 2005','t003');
insert into course values ('c006','C#','t003');
insert into course values ('c007','JavaScript','t002');
insert into course values ('c008','DIV+CSS','t001');
insert into course values ('c009','PHP','t003');
insert into course values ('c010','EJB3.0','t002');
commit;
/***************初始化成绩表***********************/
insert into sc values ('s001','c001',78.9);
insert into sc values ('s002','c001',80.9);
insert into sc values ('s003','c001',81.9);
insert into sc values ('s004','c001',60.9);
insert into sc values ('s001','c002',82.9);
insert into sc values ('s002','c002',72.9);
insert into sc values ('s003','c002',81.9);
insert into sc values ('s001','c003','59');
commit;
1、查询“c001”课程比“c002”课程成绩高的所有学生的学号；
select s.* from
(select * from sc s where cno='c001') s,
(select * from sc s1 where cno='c002')s1
where s.sno=s1.sno and s.score<s1.score;
2、查询平均成绩大于60 分的同学的学号和平均成绩；
select sno,avg(score) from sc group by sno having avg(score)>60 ;
3、查询所有同学的学号、姓名、选课数、总成绩；
select sc.*,sname from (select sc.sno,count(cno)as"选课数",sum(score)as"总成绩" from sc group by sno)
sc,student s where sc.sno=s.sno
4、查询姓“刘”的老师的个数；
select count(*)from teacher where tname like '刘%'
5、查询没学过“谌燕”老师课的同学的学号、姓名；
select * from student st1 where st1.sno not in(
select distinct st.sno from student st left join sc s on s.sno=st.sno
left join course c on s.cno=c.cno
where c.tno =(select tno from teacher where tname='谌燕'))
6、查询学过“c001”并且也学过编号“c002”课程的同学的学号、姓名；
select stu.sno,stu.sname,sc.cno from sc inner join student stu on sc.sno=stu.sno inner join sc s on s.sno=sc.sno where s.cno='c001' and sc.cno='c002'
7、查询学过“谌燕”老师所教的所有课的同学的学号、姓名；
select stu.sno,stu.sname from student stu join sc sc
on stu.sno=sc.sno join teacher te inner join course cou
on cou.tno=te.tno on sc.cno=cou.cno where tname='谌燕' group by stu.sname,stu.sno ;
8、查询课程编号“c002”的成绩比课程编号“c001”课程低的所有同学的学号、姓名；
select s.* from
(select * from sc s where cno='c001') s,
(select * from sc s1 where cno='c002')s1
where s.sno=s1.sno and s.score<s1.score;
9、查询所有课程成绩小于60 分的同学的学号、姓名；
select stu.sno,stu.sname,s.score from sc s inner join student stu on stu.sno=s.sno where score<60;
10、查询没有学全所有课的同学的学号、姓名；
select stu.sno,stu.sname,count(cno) from student stu left join sc on stu.sno=sc.sno
group by stu.sno,stu.sname having count(cno)<(select count(distinct cno)from course)
11、查询至少有一门课与学号为“s001”的同学所学相同的同学的学号和姓名；
select stu.sno,max(sname),max(sc.cno),max(sc.score) from sc sc inner join student stu on sc.sno=stu.sno where stu.sno <>'s001'and sc.cno in(
select cno from sc where sno='s001')group by stu.sno
12、查询至少学过学号为“s001”同学所有一门课的其他同学学号和姓名；
select stu.sno,stu.sname from sc sc inner join student stu on sc.sno=stu.sno where sc.sno<>'s001' and sc.cno in(
select cno from sc where sno='s001')
13、把“SC”表中“谌燕”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(s.score) from course co inner join teacher te
on co.tno=te.tno inner join sc s on s.cno=co.cno where co.tno=te.tno and te.tname='谌燕' ) where cno in(select cou.cno from course cou,teacher tea
where cou.tno=tea.tno and tea.tname='谌燕' group by cou.cno);
14、查询和“s001”号的同学学习的课程完全相同的其他同学学号和姓名；
select * from
(select * from sc where sno='s001') sc, student st where sc.sno=st.sno;
15、删除学习“谌燕”老师课的SC 表记录；
delete from sc where sc.cno in(
select co.cno from course co,sc sc,teacher t
where t.tno=co.tno and t.tname='谌燕' group by co.cno) ;
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“c002”课程的同学学号、“c002”号课的平均成绩；
insert into sc select student.sno,'c002',(select avg(score) from sc where cno='c002')
from student where sno not in( select sno from sc where cno='c002' )
17、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 cno, max(score),min(score) from sc group by cno
18、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 sc.cno,max(co.cname), avg(score),sum(case when score>=60 then 1 else 0 end)/count(*)*100as"及格率"
from course co,sc sc where co.cno=sc.cno group by sc.cno order by avg(score) desc;
19、查询不同老师所教不同课程平均分从高到低显示、
select sc.cno,max(t.tname),max(score),max(co.cname),avg(score)
from sc sc ,course co,teacher t where sc.cno=co.cno and co.tno=t.tno
group by sc.cno order by avg(score) desc;
20、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.cno,c.cname ,
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 "[70-85]",
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 inner join course c on sc.cno=c.cno where sc.cno=c.cno group by sc.cno,c.cname
21、查询各科成绩前三名的记录:(不考虑成绩并列情况)
select co.cname from
(select cname,sc.score,sc.sno from sc sc inner join course c on c.cno=sc.cno order by score desc group by cname ) c,course co
group by co.cname
22、查询每门课程被选修的学生数
select cname, count(*)from course group by cname;
23、查询出只选修了一门课程的全部学生的学号和姓名
select sc.*,sname from(
select sno,count(cno)as"选课数量" from sc group by sno having count(cno)=1 )sc,student s where sc.sno=s.sno
24、查询男生、女生人数
select ssex, count(*) from student group by ssex;
25、查询姓“张”的学生名单
select *from student where sname like '张%'
26、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
27、1981 年出生的学生名单(注：Student 表中Sage 列的类型是number)
select *from student where to_char(sysdate,'yyyy')-sage=1998
28、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 cno,avg(score) from sc group by cno order by avg(score) asc ,cno desc
29、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 sc.sno,sname,sc.cno,avg(score) from student inner join sc on student.sno=sc.sno
group by cno,sc.sno,sname having avg(score)>85
30、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 * from sc inner join course cou on cou.cno=sc.cno where cou.cname='oracle' and score<60
31、查询所有学生的选课情况；
select stu.sno,stu.sname,sc.cno,cou.cname from student
stu inner join sc on stu.sno=sc.sno inner join
course cou on cou.cno=cou.cno where sc.sno=stu.sno and sc.cno=cou.cno
32、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 stu.sno,stu.sname,sc.cno,cou.cname,sc.score from student stu inner join sc on stu.sno=sc.sno inner join course cou on cou.cno=cou.cno
where sc.sno=stu.sno and sc.cno=cou.cno and sc.score>70
33、查询不及格的课程，并按课程号从大到小排列
select cou.cno,cou.cname,sc.score from sc inner join course cou on sc.cno=cou.cno where score<60 order by score desc
34、查询课程编号为c001 且课程成绩在80 分以上的学生的学号和姓名；
select stu.sno,stu.sname,sc.cno,sc.score from sc inner join student stu on sc.sno=stu.sno where cno='c001' and score>80
35、求选了课程的学生人数
select count(distinct sno) from sc
36、查询选修“谌燕”老师所授课程的学生中，成绩最高的学生姓名及其成绩
select cou.cname,max(sc.score) from student stu
inner join sc on stu.sno=sc.sno inner join course cou on sc.cno=cou.cno
inner join teacher te on te.tno =cou.tno where te.tname='谌燕' group by cou.cname ;
37、查询各个课程及相应的选修人数
select sc.cno,cou.cname,count(cou.cname) from course cou inner join sc on cou.cno=sc.cno group by sc.cno,cou.cname
38、查询不同课程成绩相同的学生的学号、课程号、学生成绩
select a.* from sc a ,sc b where a.cno<>b.cno and a.score=b.score
39、查询每门功课成绩最好的前两名
select s1.cno,s1.score from sc s1
where (select count(cno) from sc s2 where s2.cno=s1.cno AND s1.score<s2.score)<2 order by cno asc,score desc;
40、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，若人数相同，按课程号升序排列
select cno,count(sno) from sc group by cno having count(cno)>10 order by count(sno) desc
41、检索至少选修两门课程的学生学号
select sno,count(cno) from sc group by sno having count(cno)>1
42、查询全部学生都选修的课程的课程号和课程名
select cou.cno,cou.cname from sc left join course cou on sc.cno=cou.cno group by cou.cno,cou.cname
43、查询没学过“谌燕”老师讲授的任一门课程的学生姓名
select stu.sno,stu.sname,cou.cname from teacher te inner join course cou on te.tno=cou.tno inner join sc on sc.cno=cou.cno inner join student stu on sc.sno=stu.sno where te.tname<>'谌燕'
44、查询两门以上不及格课程的同学的学号及其平均成绩
select sc.sno,avg(score) from sc where sno in(
select sno from sc where score<60 group by sno having count(sno)>1)group by sc.sno
45、检索“c004”课程分数小于60，按分数降序排列的同学学号
select * from sc where cno='c001'and score>60 order by score desc ;
46、删除“s002”同学的“c001”课程的成绩
delete from sc where sno='s002' and cno='c001';