根据预定义份额分配给国家但对渠道均等的固定价值

Posted 2023-03-31

【中文标题】根据预定义份额分配给国家但对渠道均等的固定价值

【英文标题】：Divided fix value based on pre-defined share to countries but euqally to channels

【发布时间】：2021-05-05 13:38:14

【问题描述】：

DB-Fiddle

CREATE TABLE costs (
    id SERIAL PRIMARY KEY,
    event_date DATE,
    country VARCHAR,
    channel VARCHAR,
    costs DECIMAL
);

INSERT INTO costs
(event_date, country, channel, costs)
VALUES 
('2020-02-08', 'DE', 'channel_01', '400'),
('2020-02-08', 'DE', 'channel_02', '400'),
('2020-02-08', 'FR', 'channel_01', '400'),
('2020-02-08', 'FR', 'channel_02', '400'),
('2020-02-08', 'NL', 'channel_01', '400'),
('2020-02-08', 'NL', 'channel_02', '400'),

('2020-04-15', 'DE', 'channel_01', '300'),
('2020-04-15', 'DE', 'channel_02', '300'),
('2020-04-15', 'FR', 'channel_01', '300'),
('2020-04-15', 'FR', 'channel_02', '300'),
('2020-04-15', 'NL', 'channel_01', '300'),
('2020-04-15', 'NL', 'channel_02', '300');

预期结果：

event_date    |    country   |     channel       |            costs              |
--------------|--------------|-------------------|-------------------------------|---------
2020-02-08    |      DE      |     channel_01    |      120  (=400 x 0.6 / 2)    | 
2020-02-08    |      DE      |     channel_02    |      120  (=400 x 0.6 / 2)    |   
2020-02-08    |      FR      |     channel_01    |       60  (=400 x 0.3 / 2)    |   
2020-02-08    |      FR      |     channel_02    |       60  (=400 x 0.3 / 2)    |   
2020-02-08    |      NL      |     channel_01    |       20  (=400 x 0.1 / 2)    |   
2020-02-08    |      NL      |     channel_02    |       20  (=400 x 0.1 / 2)    |  
--------------|--------------|-------------------|-------------------------------|---------
2020-04-15    |      DE      |     channel_01    |       90  (=300 x 0.6 / 2)    |   
2020-04-15    |      DE      |     channel_02    |       90  (=300 x 0.6 / 2)    |   
2020-04-15    |      FR      |     channel_01    |       45  (=300 x 0.3 / 2)    |   
2020-04-15    |      FR      |     channel_02    |       45  (=300 x 0.3 / 2)    |   
2020-04-15    |      NL      |     channel_01    |       15  (=300 x 0.1 / 2)    |   
2020-04-15    |      NL      |     channel_02    |       15  (=300 x 0.1 / 2)    |   

---

通过来自this question 的以下查询，我可以根据预定义的份额(DE=0.6, FR=0.3, NL=0.1) 每天将成本分配到每个国家/地区。

SELECT
c.event_date,
c.country,
c.channel,
(CASE WHEN c.country IN('DE') THEN c.costs * 0.6 
      WHEN c.country IN('FR') THEN c.costs * 0.3
      WHEN c.country IN('NL') THEN c.costs * 0.1 END) AS costs
FROM costs c
GROUP BY 1,2,3,4
ORDER BY 1,2,3;

但是，正如您在预期结果中看到的那样，我还想将每个国家/地区的费用平均分配给每个渠道。

我需要如何修改查询来实现这一点？

【参考方案1】：

您只需使用窗口函数：

SELECT 
c.event_date, 
c.country, 
c.channel,
c.costs,

  (CASE WHEN c.country IN ('DE') THEN c.costs * 0.6 
        WHEN c.country IN ('FR') THEN c.costs * 0.3
        WHEN c.country IN ('NL') THEN c.costs * 0.1
  END) * (1.0 / COUNT(*) OVER (PARTITION BY c.event_date, c.country)) AS costs_allocated
  
FROM costs c
GROUP BY 1,2,3,4
ORDER BY 1,2,3;

DB-Fiddle