mysql第四次作业

50道练习题

1、查询" 01 "课程比" 02 "课程成绩高的学生的信息及课程分数
select * from student left join (select t01.SId, score1, score2 from (select SId,score as score1 from sc where sc.CId='01') as t01, (select SId,score as score2 from sc where sc.CId='02') as t02 where t01.SId=t02.SId and t01.score1>t02.score2) as r on(student.SId=r.SId);

1.1、查询同时存在" 01 "课程和" 02 "课程的情况
select * from (select * from sc where sc.CId='01') as s1, (select * from sc where sc.CId='02') as s2 where s1.SId=s2.SId;

1.2、查询存在" 01 "课程但可能不存在" 02 "课程的情况(不存在时显示为 null )
select * from (select * from sc where sc.CId='01') as s1 left join (select * from sc where sc.CId='02') as s2 on(s1.SId=s2.SId);

1.3、查询不存在" 01 "课程但存在" 02 "课程的情况
select * from sc where sc.SId not in (select SId from sc where sc.CId='01') and sc.CId='02';
或
select * from sc where SId not in (select SId from sc where CId='01') and CId='02';

2、查询平均成绩大于等于 60 分的同学的学生编号和学生姓名和平均成绩
select SId,Sname,avg(score) from (select * from student as stu inner join sc on(stu.SId=sc.SId)) where avg(score)>60 group by SId;

3、查询在sc表存在成绩的学生的信息
select * from student right join (select SId,score from sc) on (student.SId=sc.SId);
 
4、查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩(没成绩的显示为 null )
 select * from (select SId,Sname from student)r right join (select SId,count(CId),sum(score) from sc group by SId)a on (r.SId=a.SId);                                                                                                                                                                                                                                                         4.2、查询有成绩的学生的信息
select * from student right join 
(select SId,score from sc )r on (student.SId=r.SId);

5、查询李姓老师的数量
select count(Tname) from Teacher where Tname like '李%';

6、查询学过「张三」老师授课的同学的信息
select * from student (select CId from sc where CId='02';

7、查询没有学全所有课程的同学的信息
select * from student where student.sid not in (select sc.sid from sc group by sc.sid having count(sc.cid)= (select count(cid) from course));

8、查询至少有一门课与学号为" 01 "的同学所学相同的同学的信息
select * from student where student.sid in (select sc.sid from sc where sc.cid in (select sc.cid from sc where sc.sid='01'));

10、查询没学过"张三"老师讲授的任一门课程的学生姓名
select sname from student where student.sid  not in (select sid from sc where cid='02' group by sid);

11、查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩
select student.sid,student.sname,b.avg from student right join (select sid,avg(score) as avg from sc where sc.sid in (select sid from sc where sc.score<60 group by sid having count(score)>1 ) group by sid )b on student.sid=b.sid;

12、检索" 01 "课程分数小于 60，按分数降序排列的学生信息
select student.*,score from student right join (select sid,score from sc where cid='01' and score<60 order by score desc)r on student.sid=r.sid;

13、按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩
select student.sid,sum(r.score),avg(r.score) from ( select course.cname,sc.sid,sc.score from course,sc where course.cid=sc.cid)r,student where student.sid=r.sid group by sid order by avg(r.score);

14、查询各科成绩最高分、最低分和平均分
 select course.cname,r.* from course right join (select cid,max(score),min(score),avg(score) from sc group by cid)r on course.cid=r.cid;

15、按各科成绩进行排序，并显示排名， Score 重复时保留名次空缺
select a.cid, a.sid, a.score, count(b.score)+1 as rank from sc as a left join sc as b on a.score

16、查询学生的总成绩，并进行排名，总分重复时不保留名次空缺
set @crank=0;
select q.sid, total, @crank := @crank +1 as rank from(select sc.sid, sum(sc.score) as total from sc group by sc.sid order by total desc)q;

17、统计各科成绩各分数段人数：课程编号，课程名称，[100-85]，[85-70]，[70-60]，[60-0] 及所占百分比
select course.cname, course.cid,
sum(case when sc.score<=100 and sc.score>85 then 1 else 0 end) as "[100-85]",
sum(case when sc.score<=85 and sc.score>70 then 1 else 0 end) as "[85-70]",
sum(case when sc.score<=70 and sc.score>60 then 1 else 0 end) as "[70-60]",
sum(case when sc.score<=60 and sc.score>0 then 1 else 0 end) as "[60-0]"
from sc left join course
on sc.cid = course.cid
group by sc.cid;

18、查询各科成绩前三名的记录
select * from sc where (select count(*) from sc as a where sc.cid = a.cid and sc.score

19、查询每门课程被选修的学生数
select cid,count(sid) from sc group by cid;

20、查询出只选修两门课程的学生学号和姓名
select student.sid,student.sname from stuednt right join ( select sid,count(cid) from sc  group by sid having count(cid)=2)r on student.sid=r.sid;

21、查询男生,女生的人数
select Ssex,count(Ssex) from student group by Ssex;

22、查询名字中含有「风」字的学生信息
select * from student where sname like '%风%';

23、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;

24、查询 1990 年出生的学生名单
select sname from student where year(sage)=1990;

25、查询每门课程的平均成绩，结果按平均成绩降序排列，平均成绩相同时，按课程编号升序排列
select cid,avg(score)  from sc as a group by cid order by a desc,cid asc;

26、查询平均成绩大于等于 85 的所有学生的学号、姓名和平均成绩
select student.sid,student.sname,r.avg from student right join (select sid,avg(score) as avg from sc group by sid having avg(score)>85)r on student.sid=r.sid;

27、查询课程名称为「数学」，且分数低于 60 的学生姓名和分数
select student.sname,sc.score from student,sc where student.sid=sc.sid and
sc.cid='02' and  sc.score<60;

28、查询所有学生的课程及分数情况（存在学生没成绩，没选课的情况）
select student.sname,sc.cid,sc.score from student left join sc on student.sid=sc.sid;

29、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 student.sname,r.cname,r.score from student right join (select course.cname,sc.score,sc.sid from course,sc where course.cid=sc.cid and sc.score>70)r on student.sid=r.sid;

30、查询不及格的课程
select course.cname,sc.score from course right join sc on course.cid=sc.cid where sc.score<60;

31、查询课程编号为 01 且课程成绩在 80 分以上的学生的学号和姓名
select sc.sid,student.sname from student,sc where student.sid=sc.sid and sc.cid='01' and sc.score>80;

32、求每门课程的学生人数
select cid,count(sid) from sc group by cid;

33、成绩不重复，查询选修「张三」老师所授课程的学生中，成绩最高的学生信息及其成绩
select student.*,r.max(score) from student right join (select cid,max(score)  from sc group by cid having sc.cid='02')r on student.sid;

34、成绩有重复的情况下，查询选修「张三」老师所授课程的学生中，成绩最高的学生信息及其成绩
update sc set score=90 where sid = "07" and cid ="02";

35、查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩
select a.* from sc as a right join sc as b on a.sid=b.sid where a.cid!=b.cid and a.score=b.score group by sid,cid,score;

36、查询每门功成绩最好的前两名
select a.sid,a.cid,a.score from sc as a left join sc as b on a.cid = b.cid and a.score

37、统计每门课程的学生选修人数（超过 5 人的课程才统计）。
select cid,count(sid) from sc group by cid having count(sid)>5;

38、检索至少选修两门课程的学生学号
select sid,coount(cid) from sc group by sid having count(sid)>=2;

39、查询选修了全部课程的学生信息
select student.* from student right join (select sid,coount(cid) from sc group by sid having count(sid)=3)r on student.sid=r.sid;

41、按照出生日期来算，当前月日 < 出生年月的月日则，年龄减一
select * from student as stu where weekofyear(stu.Sage)=weekofyear(curdate());

42、查询本周过生日的学生
select * from student as stu where weekofyear(stu.Sage)=weekofyear(curdate());

43、查询下周过生日的学生
select * from student as stu where weekofyear(stu.Sage)=weekofyear(curdate())+1;

44、查询本月过生日的学生
select * from student as stu where month(stu.Sage)=month(curdate())；

45、查询下月过生日的学生
select * from student as stu where month(stu.Sage)=month(curdate())+1;
 

作业题
create table course(
cno int primary key,
cname varchar(20)
);
create table sc(
sno int,
cno int,
score int,
primary key(sno,cno)
);
1.用SQL语句创建学生表student，定义主键，姓名不能重名，性别只能输入男或女，所在系的默认值是 “计算机”。
create table student(
sno int primary key,
sname varchar(20) unique,
ssex  enum('男','女'),
age int,
所在系 varchar(20) default "计算机"
);
2.修改student 表中年龄（age）字段属性，数据类型由int 改变为smallint
alter table student modify age smallint
3.为SC表建立按学号（sno）和课程号（cno）组合的升序的主键索引，索引名为SC_INDEX 
create index sc_index on sc (sno,cno asc);
4.创建一视图 stu_info,查询全体学生的姓名，性别，课程名，成绩
select student.sname,student.ssex r.cno,r.score from student right join
(select sno,cno,score from course,sc where course.cno=sc.cno)r on student.sno=r.sno;

创建表并插入数据
create table student1(
id int primary key not null unique,
name varchar(20) not null,
glass varchar(20) not null
);
create table sch (
id int primary key,
name varchar(20) unique,
glass varchar(20)
);
作业题
1、创建一个可以统计表格内记录条数的存储函数 ，函数名为count_sch()
create  function p1()
 returns int
begin 
    declare i int default 0;
    select count(*) into i from sch;
    return i;
end$
select p1();
2.创建一个存储过程avg_sai，有3个参数，分别是deptno，job，接收平均工资，功能查询emp表dept为30，job为销售员的平均工资。
create procedure avg_sai (in deprtno int,in job varchar(20),out a int)
begin
select avg(salary)  into a from emp where dept=30 and work='销售员';
end$
call avg_sai(dept,job,@a);

面试题
1.向student表中插入一条数据
insert into Student values(2,'张三'，'男','水浒传');
2.查询课程名为数据库，且分数低于60的学生姓名与分数
select S.name,SC.degree from Student as S right join Score as SC on S.sco=SC.sco where SC.cno='数据库' and SC.degree<60;
3.对于所有性别为女的学生，同时课程名为高等数学的分数统一加5
update Score SC set degree=degree+5 where SC.sno in (select sno from Student S where Ssex='女') and SCCcno in (select C.Cno from Course C where C.Cname='高等数学');
4.删除姓名为‘张翰’（学号=1）课程名为数据库的课程成绩
delete from Score where Sno=1 and Cno in (select c.Cno from Course c where c.Cname='数据库');