SQL常见练习题

select * from student;--学生表
select * from teacher;--教师表
select * from course;--课程表
select * from sc;--成绩表

--1、查询“c001”课程比“c002”课程成绩高的所有学生的学号；
Select s1.sno from
(Select sno,score from SC where CNO='c001') s1,
(Select sno,score from SC where CNO='c002') s2
where s1.sno=s2.sno and s1.score>s2.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 s1.sno,s1.sname,选课数,总成绩 from student s1,
(select s1.sno,选课数,总成绩 from
(select sno,count(1)选课数 from sc group by sno) s1,
(select sno,sum(score)总成绩 from sc group by sno) s2
where s1.sno=s2.sno) s2 where s1.sno=s2.sno;

--4、查询姓“刘”的老师的个数；
select count(1) 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 sno,Sname from Student where sno not in
(Select sno from SC where cno in
(Select cno from Course where tno in
(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 sno,sname from student where sno in
(select SNO from sc where cno='c001'
intersect
select SNO from sc where 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 sno,Sname from Student where sno in
(Select sno from SC where cno in
(Select cno from Course where tno in
(Select tno from Teacher where tname='谌燕')))

--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 sno,sname from student where sno in (
select s1.sno from
(select sno,score from sc where cno='c001') s1,
(select sno,score from sc where cno='c002') s2
where s1.sno=s2.sno and s1.score>s2.score)

--9、查询所有课程成绩小于60 分的同学的学号、姓名；
select sno,sname from student where sno in (
select sno from sc group by sno having max(score)<60)

--10、查询没有学全所有课的同学的学号、姓名；
select sno,Sname from Student where sno in
(select sno from (Select sno,count(*) 选课数 from SC group by sno) s,
(select COUNT(*) 课程数 from Course) c where s.选课数<c.课程数)

--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 distinct sno,Sname from Student where sno in
(select sno from SC where cno in(
select cno from sc where sno='s001')) and sno!='s001'

--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 distinct sno,Sname from Student where sno in
(select sno from SC where cno in(
select cno from SC where sno='s001')) and Sno!='s001'

--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 sno,Sname from Student where sno in
(select a.sno from
(select sno,cno from SC where cno in
(select cno from SC where sno='s001')) a where cno in
(select cno from SC where sno='s001') group by a.sno having
COUNT(*)=(select count(sno) from SC where sno='s001')) and
sno!='s001'

--15、删除学习“谌燕”老师课的SC 表记录;
delete from sc where sno in
(select s.sno from sc s,
(select cno from course where tno=
(select tno from teacher where tname='谌燕')) a
where s.cno=a.cno group by s.sno)

--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 (sno,cno,score)
select distinct st.sno,sc.cno,(select avg(score)from sc where cno='c002')
from student st,sc
where not exists
(select * from sc where cno='c002' and sc.sno=st.sno) and sc.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)"最高分",min(score)"最低分" from sc group by cno order by 1 asc

--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 cno,avg(score),sum(case when score>=60 then 1 else 0 end)/count(*) as 及格率
from sc group by cno order by 2 asc

--19、查询不同老师所教不同课程平均分从高到低显示
select a.cno,a.tname,a.cname,b.平均成绩 from
(select c.cno,t.tname,c.cname from course c,teacher t where c.tno=t.tno) a,
(select cno,avg(score) 平均成绩 from sc group by cno) b  where a.cno=b.cno order by b.平均成绩 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 s.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 "[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 s, course c where  s.cno=c.cno
group by s.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 * from
(select sno,cno,score,row_number()over(partition by cno order by score desc) rn from sc)
where rn<4

--22、查询每门课程被选修的学生数
select cno,count(sno) from sc group by cno

--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.sno,st.sname,count(cno) from student st
left join sc
on sc.sno=st.sno
group by st.sname,sc.sno having count(cno)=1;

--24、查询男生、女生人数
select 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')-1981=sage
--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 s.sno,s.sname,b.平均成绩 from student s,
(select sno,avg(score) 平均成绩 from sc group by sno having avg(score)>85) b
where s.sno=b.sno

--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 sname,score from student st,sc,course c
where st.sno=sc.sno and sc.cno=c.cno and c.cname='Oracle' and sc.score<60

--31、查询所有学生的选课情况；
select sno,count(cno) 选课数 from sc group by sno

--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  c.sname,a.cname,b.score from course a,sc b,student c
where  b.cno=a.cno and b.sno=c.sno and b.score>70

--33、查询不及格的课程，并按课程号从大到小排列
select cno,score from sc order by cno,score having score<60 group by cno 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 st.sno,st.sname,sc.cno,sc.score from sc,student st
where sc.sno=st.sno and 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 st.sname,score from student st,sc ,course c,teacher t
where
st.sno=sc.sno and sc.cno=c.cno and c.tno=t.tno
and t.tname='谌燕' and sc.score=
(select max(score)from sc where sc.cno=c.cno)

--37、查询各个课程及相应的选修人数
select cno,count(sno) from sc group by cno;

--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.score=b.score and a.cno<>b.cno

--39、查询每门功课成绩最好的前两名
select * from (
select sno,cno,score,row_number()over(partition by cno order by score desc) my_rn from sc t
)
where my_rn<=2

--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(sno)>10
order by count(sno) desc,cno asc;

--41、检索至少选修两门课程的学生学号
select sno from sc group by sno having count(cno)>1;
||
select sno from sc group by sno having count(sno)>1;

--42、查询全部学生都选修的课程的课程号和课程名
select distinct(c.cno),c.cname from course c ,sc
where sc.cno=c.cno
||
select cno,cname from course c
where c.cno in
(select cno from sc group by cno)

--43、查询没学过“谌燕”老师讲授的任一门课程的学生姓名
select st.sname from student st
where st.sno not in
(select distinct sc.sno from sc,course c,teacher t
where sc.cno=c.cno and c.tno=t.tno and t.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 sno,avg(score)from sc
where sno in
(select sno from sc where sc.score<60
group by sno having count(sno)>1
) group by 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 sno from sc where cno='c004' and score<90 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';