sql练习题面试题

/*******初始化学生表的数据******/
 create table student(
 sno varchar2(10) primary key,
 sname varchar2(20),
 sage number(2),
 ssex varchar2(5)
 );
 
 insert into student values ('s001','趙三',23,'男');
 insert into student values ('s002','李四',23,'男');
 insert into student values ('s003','胡四',25,'男');
 insert into student values ('s004','琴沁',20,'女');
 insert into student values ('s005','王理',20,'女');
 insert into student values ('s006','李波',21,'男');
 insert into student values ('s007','劉玉',21,'男');
 insert into student values ('s008','肖蓉',21,'女');
 insert into student values ('s009','陳小',23,'女');
 insert into student values ('s010','陳美',22,'女');
 commit;
 /******************初始化教师表***********************/
  create table teacher(
 tno varchar2(10) primary key,
 tname varchar2(20)
 );
 
 insert into teacher values ('t001', '劉章');
 insert into teacher values ('t002', '明燕');
 insert into teacher values ('t003', '胡明星');
 commit;
 /***************初始化课程表****************************/
  create table course(
 cno varchar2(10),
 cname varchar2(20),
 tno varchar2(20),
 constraint pk_course primary key (cno,tno)
 );
 
 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***********************/
  create table sc(
 sno varchar2(10),
 cno varchar2(10),
 score number(4,2),
 constraint pk_sc primary key (sno,cno)
 );
 
 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;
  
  
 练习：
 注意：以下练习中的数据是根据初始化到数据库中的数据来写的SQL 语句，请大家务必注意。
  
  
 1、查询“c001”课程比“c002”课程成绩高的所有学生的学号；
 2、查询平均成绩大于60 分的同学的学号和平均成绩；
 3、查询所有同学的学号、姓名、选课数、总成绩；
 4、查询姓“刘”的老师的个数；
 5、查询没学过“明燕”老师课的同学的学号、姓名；
 6、查询学过“c001”并且也学过编号“c002”课程的同学的学号、姓名；
 7、查询学过“明燕”老师所教的所有课的同学的学号、姓名；
 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；
 9、查询所有课程成绩小于60 分的同学的学号、姓名；
 10、查询没有学全所有课的同学的学号、姓名；
 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；
 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；
 13、把“SC”表中“明燕”老师教的课的成绩都更改为此课程的平均成绩；
 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；
 15、删除学习“明燕”老师课的SC 表记录；
 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；
 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
 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
 19、查询不同老师所教不同课程平均分从高到低显示
 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]
 21、查询各科成绩前三名的记录:(不考虑成绩并列情况)
 22、查询每门课程被选修的学生数
 23、查询出只选修了一门课程的全部学生的学号和姓名
 24、查询男生、女生人数
 25、查询姓“张”的学生名单
 26、查询同名同性学生名单，并统计同名人数
 27、1981 年出生的学生名单(注：Student 表中Sage 列的类型是number)
 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
 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
 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
 31、查询所有学生的选课情况；
 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；
 33、查询不及格的课程，并按课程号从大到小排列
 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；
 35、求选了课程的学生人数
 36、查询选修“明燕”老师所授课程的学生中，成绩最高的学生姓名及其成绩
 37、查询各个课程及相应的选修人数
 38、查询不同课程成绩相同的学生的学号、课程号、学生成绩
 39、查询每门功课成绩最好的前两名
 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
 41、检索至少选修两门课程的学生学号
 42、查询全部学生都选修的课程的课程号和课程名
 43、查询没学过“明燕”老师讲授的任一门课程的学生姓名
 44、查询两门以上不及格课程的同学的学号及其平均成绩
 45、检索“c004”课程分数小于60，按分数降序排列的同学学号
 46、删除“s002”同学的“c001”课程的成绩

select * from student;
select * from teacher;
select * from course;
select * from sc;

update sc
set score=55
where sno='s012' and cno='c001';

/*1、查询“c001”课程比“c002”课程成绩高的所有学生的学号*/
select sno
from sc s1
where s1.cno='c001' and s1.score >
  (select s2.score
  from sc s2
  where s2.cno='c002' and s1.sno=s2.sno
);

select s1.sno
from sc s1 join sc s2 on s1.sno=s2.sno
where s1.score>s2.score 
and s1.cno='c001'
and s2.cno='c002';

/*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 stu.sno,stu.sname,count(sc.cno),sum(sc.score)
from student stu left join sc on stu.sno=sc.sno
group by stu.sno,stu.sname /*group by分组后，select时只能选择进行分组的字段。例如要显示出sno和sname，需要对它们进行分组*/
order by stu.sno; /*进行排序order by的字段必须是进行分组的字段，使用替他字段不行*/

select stu.sno,stu.sname,ct.*
from (select sno,count(sc.cno),sum(sc.score) from sc group by sno) ct,student stu
where stu.sno=ct.sno; /*注意group by中进行分组的字段必须至少在select中显示一个*/
/*不显示没有选任何科目的学生*/

/*4、查询姓“刘”的老师的个数*/
select count(1)
from teacher
where tname like '劉%';

select count(tno)
from teacher
where tname like '劉%';

/*5、查询没学过“明燕”老师课的同学的学号、姓名*/
select st.sno,st.sname
from student st
where st.sno not in
  (select distinct sno 
    from sc 
    join course cs on sc.cno=cs.cno
    join teacher tc on cs.tno=tc.tno and tname='明燕'
);/*此处用distinct用于返回唯一不同的值，join on可以连续使用*/

/*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 st.sno,st.sname
from sc s1 join sc s2 on s1.sno=s2.sno
join student st on st.sno=s2.sno
where s1.cno='c001' and s2.cno='c002';

/*7、查询学过“明燕”老师所教的所有课的同学的学号、姓名*/
select st.sno,st.sname,ns.sum from
(select sno,count(sno) sum /*按学号分组，找出，找出每个学生的学过“明燕”老师课所教的课程的课程总数*/
  from
  (select sno /*找出学过“明燕”老师课所教的课程的学号*/
    from sc
    where cno in (/*找出是“明燕”老师课所教的课程号*/
      select cs.cno 
      from teacher tc 
      join course cs 
      on tc.tno=cs.tno 
      where tc.tname='明燕')) 
  group by sno) ns /*新表名为ns*/
join student st
on ns.sno=st.sno
where ns.sum = ( /*找出“明燕”老师所教的所有课程的总和*/
  select count(cs.cno)
  from course cs join teacher tc on cs.tno=tc.tno
  where tc.tname='明燕'
);

/*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 st.sno,st.sname
from student st join sc s1 on st.sno=s1.sno
join sc s2 on s1.sno=s2.sno
where s1.cno='c001'
and s2.cno='c002'
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 st.sno,st.sname
from student st 
where sno not in 
(select distinct sno /*找出不是 成绩大于或等于60分的学号*/
  from sc 
  where sc.score>=60);

select stu.sno,stu.sname
from sc,student stu
where sc.sno=stu.sno
group by stu.sno,stu.sname
having max(sc.score)<60;

/*10、查询没有学全所有课的同学的学号、姓名*/
select st.sno,st.sname
from student st
where st.sno in (select sno,count(cno) sum from sc where
 sum=(select count(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*/
/*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 s1.sno,st.sname
from sc s1 join student st on s1.sno=st.sno
where s1.cno in
  (select s2.cno 
    from sc s2
    where s2.sno='s001') 
  and s1.sno<>'s001';


/*13、把“SC”表中“明燕”老师教的课的成绩都更改为此课程的平均成绩*/
update sc s
set s.score = 
  (select avg(sc.score) 
  from course cs,teacher tc,sc
  where tc.tname='明燕' and cs.tno=tc.tno 
  group by sc.cno)
where s.cno in 
  (select cs.cno
  from course cs,teacher tc
  where tc.tname='明燕' and cs.tno=tc.tno);

/*14、查询和“s002”号的同学学习的课程完全相同的其他同学学号和姓名*/
select stu.sno,stu.sname from student stu 
where stu.sno in     /*IN 操作符允许我们在 WHERE 子句中规定多个值,找到's002'的学习的所有课程*/
 (select sc.sno from sc join student stu on stu.sno=sc.sno
 where sc.cno in
  (/*至少包括s002学过的所有课程*/
  select distinct cno from sc where sc.sno='s002')
 and sc.sno<>'s001'
 group by sc.sno
 having count(sc.cno)=
  (select count(1) from sc where sno='s002'))
 and stu.sno in 
 (/*找到与s002课程数目相等的学生学号,排除大于的*/
  select sc.sno from student stu,sc
  where stu.sno=sc.sno
  group by sc.sno
  having count(1)=
  (select count(1) from sc where sno='s002' group by sno));

/*15、删除学习“明燕”老师课的SC 表记录*/
delete 
from sc
where sc.cno in
  (select cno 
  from course cs 
  join teacher tc on cs.tno=tc.tno 
  where tc.tname='明燕');

/*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 distinct stu.sno,sc.cno,(select avg(score) from sc where  cno='c002') ag
from student stu join sc on sc.sno=stu.sno
where not exists /*不存在exists，进行全部查询*/
(select * from sc where cno='c002');

insert into sc
select distinct stu.sno,sc.cno,(select avg(score) from sc where  cno='c002') ag
from student stu join sc on sc.sno=stu.sno
where sc.sno not in
(select distinct 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 cno,avg(score),
       sum(case when score>60 then 1 else 0 end)/count(1) as pass_rate
from sc
group by cno
order by avg(score) asc,pass_rate desc;

/*19、查询不同老师所教不同课程平均分从高到低显示*/
select c.cno,tc.tname,avg(score)
from teacher tc join course c on tc.tno=c.tno
join sc on sc.cno=c.cno
group by c.cno,tc.tname
order by avg(score) desc;/*从高到低显示即进行降序排列*/

/*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,/*起别名时，别名为数字等要用双引号进行表示*/
sum(case when sc.score between 100 and 85 then 1 else 0 end) as "[100-85]",
sum(case when sc.score between 85 and 70 then 1 else 0 end) as "[85-70]",
sum(case when sc.score between 70 and 60 then 1 else 0 end) as "[70-60]", 
sum(case when sc.score<60 then 1 else 0 end) as "[<60]"
from sc join course c on 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 *
from
(select sno,cno,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 c.cno,c.cname,count(1)
from sc join course c on sc.cno=c.cno
group by c.cno,c.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 stu.sno,stu.sname
from student stu join sc on stu.sno=sc.sno
group by stu.sno,stu.sname having count(sc.cno)=1;

/*24、查询男生、女生人数*/
select ssex,count(1)
from student
group by ssex;

/*25、查询姓“李”的学生名单*/
select sname
from student
where sname like '李%';

/*26、查询同名同性学生名单，并统计同名人数*/
select sname,count(1)
from student 
group by sname having count(1)>1;/*注意找同名同姓的条件按sname分组且count(1)>1即可*/

/*27、1981 年出生的学生名单(注：Student 表中Sage 列的类型是number)*/
select *
from student stu
where to_date(sysdate,'yyyy')-sage=1981; /*to_number只能进行数字型字符串类型进行转换*/

/*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 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,stu.sname,avg(sc.score)
from student stu join sc on stu.sno=sc.sno
group by sc.sno,stu.sname having avg(sc.score) > 85; /*group by后进行求每个学生所有成绩的平均值，用having条件语句*/

/*注意最后进行的select查询，故下面的写法是错误的，别名ag是无效的的*/
select sc.sno,stu.sname,avg(sc.score) ag
from student stu join sc on stu.sno=sc.sno
where ag>85
group by sc.sno,stu.sname ;

/*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 stu.sname,sc.score
from student stu
join sc on stu.sno=sc.sno
join course c on c.cno=sc.cno
where c.cname='Oracle'
and sc.score<60;

/*31、查询所有学生的选课情况*/
select stu.sno,stu.sname,c.cname,sc.score
from student stu,sc,course c
where stu.sno=sc.sno
and c.cno=sc.cno
order by stu.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 stu.sname,c.cname,sc.score
from student stu 
join sc on stu.sno=sc.sno
join course c on sc.cno=c.cno
where sc.score>70;

/*33、查询不及格的课程，并按课程号从大到小排列*/
select c.cno,c.cname,sc.score
from course c join sc on c.cno=sc.cno
where score<60 
order by c.cno asc;/*group by和order by须放在where子句的后面,或后面用having，asc升序 desc降序*/

/*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
from student stu join sc on stu.sno=sc.sno
where sc.cno='c001'
and sc.score>80;

select stu.sno,stu.sname
from student stu,sc
where sc.cno='c001'
and sc.score>80
and stu.sno=sc.sno;

/*35、求选了课程的学生人数*/
select count(distinct sno)
from sc; /*注意使用distinct，过滤掉多余的重复记录只保留一条*/

/*36、查询选修“明燕”老师所授课程的学生中，成绩最高的学生姓名及其成绩*/
select s.cno,stu.sname,s.score
from student stu 
join sc s on stu.sno=s.sno
join course c on c.cno=s.cno
join teacher tc on tc.tno=c.tno
where tc.tname='明燕' and score=  
(select max(score) from sc where sc.cno=s.cno);
/*找到每门课程的最大值，再找到选修‘明燕’课程并且成绩是最大值的学生信息等*/

/*37、查询各个课程及相应的选修人数*/
select cno,count(1)
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 s1.sno,s1.cno,s1.score
from sc s1 join sc s2 on s1.score=s2.score
where s1.cno<>s2.cno;


/*39、查询每门功课成绩最好的前两名*/
select *
from 
  (select stu.sname,sc.sno,sc.cno,
  row_number()over(partition by cno order by score desc) rn 
  from sc join student stu on sc.sno=stu.sno)/*添加了一列为rn，按课程号组队按降序排序找到各科的前两名学生*/
  where rn < 3;
/*row_number()over(partition by col1 order by col2)函数
根据col1分组，在分组内部根据col2排序，而此函数计算的值就表示每组内部排序后的顺序编号（组内是连续且唯一的）*/


/*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,count(1)
from sc
group by sno 
having count(1)>1;

/*42、查询全部学生都选修的课程的课程号和课程名*/
select sc.cno,c.cname
from course c join sc on sc.cno=c.cno
group by sc.cno,c.cname
having count(1)=(select count(1) from student);/*找到学生所选课程总数等于总学生数的学生*/


/*43、查询没学过“明燕”老师讲授的任一门课程的学生姓名*/
select stu.sname
from student stu 
where stu.sno not in 
  (select distinct sno /*找到学过“明燕”老师讲授的任一门课程的学生学号*/
  from sc 
  join course c on sc.cno=c.cno 
  join teacher tc on c.tno=tc.tno
  where tc.tname='明燕');


/*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 /*找出两门以上不及格课程的学生*/
  from sc 
  where score<60
  group by sno 
  having count(sno)>2)
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,score
from sc
where cno='c004' 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='soo2' and cno='coo1';