GROUP BY下个月超过N年

Question

我需要在下个月超过5年的时间内按"地平线"12分组:
假设我们是2015-08-15

SUM amount from  0 to 12 next months (from 2015-08-16 to 2016-08-15)
SUM amount from 12 to 24 next months (from 2016-08-16 to 2017-08-15)
SUM amount from 24 to 36 next months ...
SUM amount from 36 to 48 next months
SUM amount from 48 to 60 next months

这是一个摆弄的数据集示例:

+----+------------+--------+
| id | date       | amount |
+----+------------+--------+
|  1 | 2015-09-01 |     10 |
|  2 | 2015-10-01 |     10 |
|  3 | 2016-10-01 |     10 |
|  4 | 2017-06-01 |     10 |
|  5 | 2018-06-01 |     10 |
|  6 | 2019-05-01 |     10 |
|  7 | 2019-04-01 |     10 |
|  8 | 2020-04-01 |     10 |
+----+------------+--------+

这是预期的结果:

+---------+--------+
| horizon | amount |
+---------+--------+
|       1 |     20 |
|       2 |     20 |
|       3 |     10 |
|       4 |     20 |
|       5 |     10 |
+---------+--------+

我怎样才能将这12个月的12个月分为"视野"？

---

我标记了PostgreSQL但我实际上使用的是ORM,所以它只是为了找到这个想法.(顺便说一句,我没有访问日期格式化功能)

Answer 1

我将12个月的时间框架和分组分开:

SELECT
  FLOOR(
      (EXTRACT(EPOCH FROM date) - EXTRACT(EPOCH FROM now()))
        / EXTRACT(EPOCH FROM INTERVAL '12 month')
    ) + 1 AS "horizon",
  SUM(amount) AS "amount"
FROM dataset 
GROUP BY horizon
ORDER BY horizon;

SQL小提琴

灵感来自:Postgresql SQL GROUP BY时间间隔,任意精度(低至毫秒)