窗口函数，用于标识一个月内密钥的值

Question

我的数据如下：

product | month | purchased
a           jan     online  
a           jan     instore
b           jan     online
c           jan     instore

我想要做的是确定在同一个月内在同一个结果集中购买产品的方式如下：

product | month | purchased | method
a           jan     online      online-instore
a           jan     instore     online-instore
b           jan     online      online
c           jan     instore     instore

我想知道是否有办法编写可以执行此操作的窗口查询，而不是编写单独的查询，然后将其连接回结果集。

Answer 1

可以使用

MIN/MAX个窗口函数：

SELECT product, month, purchased,
       CASE max( purchased ) OVER (partition by product, month )
       WHEN min( purchased ) OVER (partition by product, month )
       THEN min( purchased ) OVER (partition by product, month )
       ELSE max( purchased ) OVER (partition by product, month )
            || '-' ||
            min( purchased ) OVER (partition by product, month )
       END As method
FROM Table

Answer 2

select
  product, month,
  array_agg(purchased) over (partition by product, month) as method
from
  your_table
group by
  product, month, purchased;

如果您想要method1-method2-...结果，请将array_agg(purchased)更改为string_agg(purchased, '-')