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一.建表和加载数据

1.student表

create table if not exists student(s_id int,s_name string,s_birth string,s_sex string)

row format delimited

fields terminated by ','

;

load data local inpath '/root/data.txt' into table student;

2.course表

create table if not exists course(c_id int,c_course string,t_id int)

row format delimited

fields terminated by ','

;

load data local inpath '/root/data.txt' into table course;

3.teacher表

create table if not exists teacher(t_id int,t_name string)

row format delimited

fields terminated by ','

;

load data local inpath '/root/data.txt' into table teacher;

4.score表

create table if not exists score(s_id int,c_id int, s_score DOUBLE)

row format delimited

fields terminated by ','

;

load data local inpath '/root/data.txt' into table score;

二.查询"01"课程比"02"课程成绩高的学生的信息及课程分数?

答案①：

select stu.*,c.*

from student stu

join score a on a.c_id = '01' and a.s_id= stu.s_id

left join score b on b.c_id = '02' and b.s_id= stu.s_id

join score c on c.s_id= stu.s_id

where a.s_score > b.s_score or b.s_score is null

;

答案②：

select stu.*,c.*

from student stu

left join score a on a.c_id = '02' and a.s_id= stu.s_id

join score b on b.c_id = '01' and b.s_id= stu.s_id

join score c on c.s_id= stu.s_id

where a.s_score < b.s_score or a.s_score is null

;

三.查询"01"课程比"02"课程成绩低的学生的信息及课程分数:

答案①：

select stu.*,c.*

from student stu

join score a on a.c_id = '02' and a.s_id= stu.s_id

left join score b on b.c_id = '01' and b.s_id= stu.s_id

join score c on c.s_id= stu.s_id

where a.s_score > b.s_score or b.s_score is null

;

答案②：

select stu.*,c.*

from student stu

left join score a on a.c_id = '01' and a.s_id= stu.s_id

join score b on b.c_id = '02' and b.s_id= stu.s_id

join score c on c.s_id= stu.s_id

where a.s_score < b.s_score or a.s_score is null

;

总结：对于二题和三题的查询连接的方法：谁大就把谁放在左边,谁小就把谁舍弃。

四.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？

答案①：

select

a.s_id,stu.s_name,avg(a.s_score) as avgscore

from score a

join student stu on a.s_id = stu.s_id

group by a.s_id,stu.s_name

having avgscore >= 60

;

答案②：

select

a.s_id,stu.s_name,avg(a.s_score)>=60

from score a

join student stu on a.s_id = stu.s_id

group by a.s_id,stu.s_name

;

五.查询平均成绩小于60分的同学的学生编号和学生姓名和平均成绩?

答案①：

select

a.s_id,stu.s_name,avg(a.s_score) as avgscore

from score a

join student stu on a.s_id = stu.s_id

group by a.s_id,stu.s_name

having avgscore < 60

union all

select stu.s_id,stu.s_name,NULL as avgscore

from student stu

left join score a on stu.s_id = a.s_id

where a.s_score is null

;

六.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

答案：

select stu.s_id,stu.s_name,count(sc.s_id) as totalSubjects,sum(sc.s_score) as sumScores

from student stu left join score sc on stu.s_id=sc.s_id

group by stu.s_id,stu.s_name;

七.查询"李"姓老师的数量？

select count(1)from teacher where t_name like '李%';

八.查询学过"张三"老师授课的同学的信息?

select distinct stu.*

from student stu

join score sc on stu.s_id=sc.s_id

join course co on sc.c_id=co.c_id

join teacher te on co.t_id =te.t_id

where te.t_name='张三';

九.查询没学过"张三"老师授课的同学的信息?

select *

from student stu

join teacher te on te.t_name='张三'

join course co on te.t_id=co.t_id

left join score sc on stu.s_id=sc.s_id and co.c_id=sc.c_id

where sc.s_score is null;

十.查询学过编号为"01"并且也学过编号为"02"的课程的同学的信息?

select stu.*,sc.*

from student stu,score sc,score sc1

where stu.s_id=sc.s_id and stu.s_id=sc1.s_id

and sc.c_id=1 and sc1.c_id=2;

十一.查询学过编号为"01"但是没有学过编号为"02"的课程的同学的信息:

select stu.*

from student stu

join score sc on sc.s_id =stu.s_id and sc.c_id = '01'

where not exists (select 1 from score sc1 where sc1.c_id = '02' and stu.s_id = sc1.s_id)

;

十二.查询没有学全所有课程的同学的信息?

select distinct stu.*

from student stu

join score sc

left join course co

on stu.s_id=sc.s_id and sc.c_id=co.c_id

where sc.s_score is null;

十三.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 distinct stu.*

from student stu

join score sc on stu.s_id=sc.s_id

where stu.s_id <> 1 and sc.c_id in

(select c_id from score where s_id=1);

十四.查询和"01"号的同学学习的课程完全相同的其他同学的信息?

select

十五.查询没学过"张三"老师讲授的任一门课程的学生姓名?

select stu.*

from student stu

join teacher te on te.t_name = '张三'

join course co on co.t_id = te.t_id

left join score sc on sc.c_id = co.c_id and sc.s_id = stu.s_id

where sc.s_score is null;

十六.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

*

from student stu

join score sc on sc.s_id = stu.s_id

where sc.s_score < 60

;

十七.检索"01"课程分数小于60，按分数降序排列的学生信息?

select *

from student stu

join score sc on sc.s_id = stu.s_id

where sc.c_id = 1 and sc.s_score < 60

order by sc.s_score desc;

十八.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 *,

round(avg(sc.s_score) over(distribute by sc.s_id),2) as avg1

from score sc

order by avg1 desc,sc.s_score desc;

总结：在这里啊，round是hive的内置函数，其功能是四舍五入。

十九..查询各科成绩最高分、最低分和平均分：以如下形式显示：课程ID，课程name，最高分，最低分，平均分，及格率，中等率，优良率，优秀率:

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