Hive学习（10）行转列与列转行

行转列

建表语句与数据录入

use data_warehouse_test;
 
CREATE TABLE IF NOT EXISTS user_order (
	uid BIGINT
	,order_id BIGINT
);
 
CREATE TABLE IF NOT EXISTS user_orders (
	uid BIGINT
	,order_ids STRING
);
 
INSERT OVERWRITE TABLE user_order VALUES 
(1, 112)
,(1, 123)
,(2, 234)
,(2, 21)
,(3, 821)
;

两种实现行转列：

第一种实现：
concat_ws(',',COLLECT_LIST(column))与concat_ws(',',COLLECT_SET(column)) 都可实现。
区别：collect_list 不去重，collect_set 去重。
注意： column的数据类型要求是string
结论：CONCAT_Ws(SEPARATOR ,collect_set(column)) =======> GROUP_CONCAT（distinct column）函数

--1.
INSERT OVERWRITE TABLE user_orders
SELECt 
	uid
	,CONCAT_WS(',', COLLECT_SET(order_str)) AS order_list
FROM
(
	SELECt uid , CAST(order_id AS STRING) AS order_str
	FROM user_order
) tmp
GROUP BY uid
;

结果：

+------------------+------------------------+
| user_orders.uid  | user_orders.order_list  |
+------------------+------------------------+
| 1                | 112,123                |
| 2                | 234,21                 |
| 3                | 821                    |
+------------------+------------------------+

第二种实现：
group_concat函数
完整的语法如下：
group_concat([DISTINCT] 要连接的字段 [Order BY ASC/DESC 排序字段] [Separator '分隔符'])

--2.
INSERT OVERWRITE TABLE user_orders
SELECt 
	uid
	,group_concat(distinct order_str ORDER BY order_str DESC SEPARATOR ',') AS order_list
FROM
(
	SELECt uid , CAST(order_id AS STRING) AS order_str
	FROM user_order
) tmp
GROUP BY uid
;

结果：

+------------------+------------------------+
| user_orders.uid  | user_orders.order_list  |
+------------------+------------------------+
| 1                | 123,112                |
| 2                | 234,21                 |
| 3                | 821                    |
+------------------+------------------------+

列转行

建表语句与数据录入

CREATE TABLE IF NOT EXISTS explode_laterview_org(
	day1_num BIGINT
	,day2_num BIGINT
	,day3_num BIGINT
	,day4_num BIGINT
	,day5_num BIGINT
	,day6_num BIGINT
	,day7_num BIGINT
	,campaign_name STRING
	,campaign_id BIGINT
);
 
 
INSERT OVERWRITE TABLE explode_laterview_org VALUES 
(40, 20, 10, 4, 4, 2, 1, 'zoo', 2 )
,(100, 80, 53, 40, 7, 6, 5, 'moji', 3)
;

需输出：

+------------------+--------------------+-----------+---------------+
| _u1.campaign_id  | _u1.campaign_name  |  _u1._c2  | _u1.day1_num  |
+------------------+--------------------+-----------+---------------+
| 2                | zoo                | day1_num  | 40            |
| 2                | zoo                | day2_num  | 20            |
| 2                | zoo                | day3_num  | 10            |
| 2                | zoo                | day4_num  | 4             |
| 2                | zoo                | day5_num  | 4             |
| 2                | zoo                | day6_num  | 2             |
| 2                | zoo                | day7_num  | 1             |
| 3                | moji               | day1_num  | 100           |
| 3                | moji               | day2_num  | 80            |
| 3                | moji               | day3_num  | 53            |
| 3                | moji               | day4_num  | 40            |
| 3                | moji               | day5_num  | 7             |
| 3                | moji               | day6_num  | 6             |
| 3                | moji               | day7_num  | 5             |
+------------------+--------------------+-----------+---------------+

实现列转行：使用lateral view和str_to_map

SELECt 
    campaign_id, campaign_name, type, num
FROM explode_laterview_org
LATERAL VIEW
    EXPLODE(
            STR_TO_MAP(
                    CONCAT(
                        'day1_num=',CAST (day1_num AS STRING),
                        '&day2_num=',CAST (day2_num AS STRING),
                        '&day3_num=',CAST (day3_num AS STRING),
                        '&day4_num=',CAST (day4_num AS STRING),
                        '&day5_num=',CAST (day5_num AS STRING),
                        '&day6_num=',CAST (day6_num AS STRING),
                        '&day7_num=',CAST (day7_num AS STRING)
                    )
                ,'&', '=')
        ) lateral_table AS type, num
;

结果：

+--------------+----------------+-----------+------+
| campaign_id  | campaign_name  |   type    | num  |
+--------------+----------------+-----------+------+
| 2            | zoo            | day1_num  | 40   |
| 2            | zoo            | day2_num  | 20   |
| 2            | zoo            | day3_num  | 10   |
| 2            | zoo            | day4_num  | 4    |
| 2            | zoo            | day5_num  | 4    |
| 2            | zoo            | day6_num  | 2    |
| 2            | zoo            | day7_num  | 1    |
| 3            | moji           | day1_num  | 100  |
| 3            | moji           | day2_num  | 80   |
| 3            | moji           | day3_num  | 53   |
| 3            | moji           | day4_num  | 40   |
| 3            | moji           | day5_num  | 7    |
| 3            | moji           | day6_num  | 6    |
| 3            | moji           | day7_num  | 5    |
+--------------+----------------+-----------+------+

函数说明：

concat_ws()函数
功能：一次性指定分隔符
语法：concat_ws(separator,str1,str2,...)
说明：第一个参数指定分隔符分隔符不能为空如果为NULL 则返回值NULL

collect_set()函数
功能：将colname指定的列值聚合为一个无重复元素的数组
语法：collect_set()
说明：colname：必填。表的列名称，可以为任意类型。

group_concat()函数
功能：将group by产生的同一个分组中的值连接起来返回一个字符串结果
语法 group_concat([distinct]要连接的字段 [order by 排序字段 asc/desc][separator'分隔符'])
说明：通过使用distinct可以排除重复值如果希望对结果中的值进行排序可以使用order by子句 separator是一个字符串值
缺省为一个逗号

参考文章：

1.【学习笔记】hive 之行拆列explode

https://yq.aliyun.com/articles/654743

HIVE 中内置了 EXPLODE 和 LATERAL VIEW，这两个 Function 非常的有用。尤其是在行转列的情形下。

2.hive中的lateral view 与 explode函数的使用

https://blog.csdn.net/guodong2k/article/details/79459282
3.
https://blog.csdn.net/qq_34206560/article/details/88358982
4.
https://help.aliyun.com/document_detail/48975.html?utm_content=g_1000230851&spm=5176.20966629.toubu.3.f2991ddcpxxvD1#title-7zg-lre-3es

Hive学习（10）行转列与列转行

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