保存select查询结果的几种方式：
1、将查询结果保存到一张新的hive表中
create table t_tmp
as
select * from t_p;
2、将查询结果保存到一张已经存在的hive表中
insert into table t_tmp
select * from t_p;
3、将查询结果保存到指定的文件目录（可以是本地，也可以是hdfs）
(本地)
insert overwrite local directory '/home/hadoop/test'
select * from t_p;
(hdfs)
insert overwrite directory '/aaa/test'
select * from t_p;
-----------------------------------
关于hive中的各种join
准备数据
1,a
2,b
3,c
4,d
7,y
8,u
2,bb
3,cc
7,yy
9,pp
建表：
create table a(id int,name string)
row format delimited fields terminated by ',';
create table b(id int,name string)
row format delimited fields terminated by ',';
导入数据：
load data local inpath '/home/hadoop/a.txt' into table a;
load data local inpath '/home/hadoop/b.txt' into table b;
实验：
** inner join
select * from a inner join b on a.id=b.id;
+-------+---------+-------+---------+--+
| a.id | a.name | b.id | b.name |
+-------+---------+-------+---------+--+
| 2 | b | 2 | bb |
| 3 | c | 3 | cc |
| 7 | y | 7 | yy |
+-------+---------+-------+---------+--+
**left join
select * from a left join b on a.id=b.id;
+-------+---------+-------+---------+--+
| a.id | a.name | b.id | b.name |
+-------+---------+-------+---------+--+
| 1 | a | NULL | NULL |
| 2 | b | 2 | bb |
| 3 | c | 3 | cc |
| 4 | d | NULL | NULL |
| 7 | y | 7 | yy |
| 8 | u | NULL | NULL |
+-------+---------+-------+---------+--+
**right join
select * from a right join b on a.id=b.id;
**
select * from a full outer join b on a.id=b.id;
+-------+---------+-------+---------+--+
| a.id | a.name | b.id | b.name |
+-------+---------+-------+---------+--+
| 1 | a | NULL | NULL |
| 2 | b | 2 | bb |
| 3 | c | 3 | cc |
| 4 | d | NULL | NULL |
| 7 | y | 7 | yy |
| 8 | u | NULL | NULL |
| NULL | NULL | 9 | pp |
+-------+---------+-------+---------+--+
**
select * from a left semi join b on a.id = b.id;
+-------+---------+--+
| a.id | a.name |
+-------+---------+--+
| 2 | b |
| 3 | c |
| 7 | y |
+-------+---------+--+
-------------
多重插入：
from student
insert into table student_p partition(part='a')
select * where Sno<95011;
insert into table student_p partition(part='a')
select * where Sno<95011;
---------------
级联求和
create table t_access_times(username string,month string,salary int)
row format delimited fields terminated by ',';
load data local inpath '/home/hadoop/t_access_times.dat' into table t_access_times;
A,2015-01,5
A,2015-01,15
B,2015-01,5
A,2015-01,8
B,2015-01,25
A,2015-01,5
A,2015-02,4
A,2015-02,6
B,2015-02,10
B,2015-02,5
要得出的结果
+-------------+----------+-----------+-------------+
| 用户 | 月份 | 月份统计 | 累计统计 |
+-------------+----------+-----------+-------------+
| A | 2015-01 | 33 | 33 |
| A | 2015-02 | 10 | 43 |
| B | 2015-01 | 30 | 30 |
| B | 2015-02 | 15 | 45 |
+-------------+----------+-----------+-------------+
1、第一步，先求个用户的月总金额
select username,month,sum(salary) as salary from t_access_times group by username,month
+-----------+----------+---------+--+
| username | month | salary |
+-----------+----------+---------+--+
| A | 2015-01 | 33 |
| A | 2015-02 | 10 |
| B | 2015-01 | 30 |
| B | 2015-02 | 15 |
+-----------+----------+---------+--+
2、第二步，将月总金额表 自己连接 自己连接
select A.username,A.month,max(A.salary) as salary,sum(B.salary) as accumulate
from
(select username,month,sum(salary) as salary from t_access_times group by username,month) A
inner join
(select username,month,sum(salary) as salary from t_access_times group by username,month) B
on
A.username=B.username
+-------------+----------+-----------+-------------+----------+-----------+--+
| a.username | a.month | a.salary | b.username | b.month | b.salary |
+-------------+----------+-----------+-------------+----------+-----------+--+
| A | 2015-01 | 33 | A | 2015-01 | 33 |
| A | 2015-01 | 33 | A | 2015-02 | 10 |
| A | 2015-02 | 10 | A | 2015-01 | 33 |
| A | 2015-02 | 10 | A | 2015-02 | 10 |
| B | 2015-01 | 30 | B | 2015-01 | 30 |
| B | 2015-01 | 30 | B | 2015-02 | 15 |
| B | 2015-02 | 15 | B | 2015-01 | 30 |
| B | 2015-02 | 15 | B | 2015-02 | 15 |
+-------------+----------+-----------+-------------+----------+-----------+--+
3、第三步，从上一步的结果中
进行分组查询，分组的字段是a.username a.month
求月累计值： 将b.month <= a.month的所有b.salary求和即可
select A.username,A.month,max(A.salary) as salary,sum(B.salary) as accumulate
from
(select username,month,sum(salary) as salary from t_access_times group by username,month) A
inner join
(select username,month,sum(salary) as salary from t_access_times group by username,month) B
on
A.username=B.username
where B.month <= A.month
group by A.username,A.month
order by A.username,A.month;
