使用 Postgresql 进行 RFM 分析答案

【问题标题】：RFM analysis with Postgresql使用 Postgresql 进行 RFM 分析
【发布时间】：2017-08-16 20:44:54
【问题描述】：

我正在尝试使用 Postgresql 查询创建 RFM 分析。但是，我还没有完全完成对 Recency 维度的查询。本文启发的查询 "https://cooldata.wordpress.com/2014/03/25/an-all-sql-way-to-automate-rfm-scoring/ "
Recency 维度的标准是

2 个月内的最后一个订单 = 5
最后一个订单在 4 个月内 = 4
6 个月内的最后一个订单 = 3
8 个月内的最后一个订单 = 2
10 个月内的最后一个订单 = 1

下面是我一直在尝试完成的查询

WITH rfm AS

(SELECT email,
 SUM((total_incl_tax)) AS cash,
 MAX(decode(order_order.order_date, 2016-01-01, 5, 2016-02-01, 4, 2016-03-01, 3, 2016-04-01, 2, 201605-01, 1)) AS recency,
 COUNT(DISTINCT(order_date)) AS frequency
 FROM order_order

 GROUP BY email)


SELECT rfm.email,
CASE
WHEN rfm.cash >= 2000000 THEN 5
WHEN rfm.cash > 1500000 THEN 4
WHEN rfm.cash > 1000000 THEN 3
WHEN rfm.cash > 500000 THEN 2
WHEN rfm.frequency > 4 THEN 5
WHEN rfm.frequency = 4 THEN 4
WHEN rfm.frequency = 3 THEN 3
WHEN rfm.frequency = 2 THEN 2
WHEN rfm.frequency = 1 THEN 1
else 1

END  + rfm.frequency AS rfm_score
--+ Five_years.recency

FROM rfm
GROUP BY rfm.email, rfm.cash,rfm.frequency
ORDER BY rfm.email

错误是：

ERROR: function decode(timestamp with time zone, integer, integer, integer, integer, integer, integer, integer, integer, integer, integer) does not exist Hint: No function matches the given name and argument types. You might need to add explicit type casts. Position: 186

我认为错误在这一行

MAX(decode(order_order.order_date, 2016-01-01, 5, 2016-02-01, 4, 2016-03-01, 3, 2016-04-01, 2, 2016-05-01, 1)) AS recency

在将误差线修改为新近度维度规定的标准方面有什么建议吗？谢谢

【问题讨论】：

你在哪里找到in the Postgres manual decode() 函数？

标签： sql postgresql heroku heroku-postgres

【解决方案1】：

Postgres 中没有 decode() 函数。您可以用另一个 CASE 语句替换它：

WITH rfm AS
(
     SELECT email,
     SUM((total_incl_tax)) AS cash,
     MAX(
         CASE
          WHEN order_order.order_date = '2016-01-01' THEN 5
          WHEN order_order.order_date = '2016-02-01' THEN 4
          WHEN order_order.order_date = '2016-03-01' THEN 3
          WHEN order_order.order_date = '2016-04-01' THEN 2
          WHEN order_order.order_date = '2016-05-01' THEN 1
         END
        )   as recency,
     COUNT(DISTINCT(order_date)) AS frequency
     FROM order_order
     GROUP BY email
 )
SELECT rfm.email,
CASE
    WHEN rfm.cash >= 2000000 THEN 5
    WHEN rfm.cash > 1500000 THEN 4
    WHEN rfm.cash > 1000000 THEN 3
    WHEN rfm.cash > 500000 THEN 2
    WHEN rfm.frequency > 4 THEN 5
    WHEN rfm.frequency = 4 THEN 4
    WHEN rfm.frequency = 3 THEN 3
    WHEN rfm.frequency = 2 THEN 2
    WHEN rfm.frequency = 1 THEN 1
    else 1
END  + rfm.frequency + rfm.recency AS rfm_score
FROM rfm
GROUP BY rfm.email, rfm.cash,rfm.frequency
ORDER BY rfm.email

进一步阅读：Decode equivalent in postgres

【讨论】：