每天每个状态的PostgreSQL计数

Question

我有下表：

Reservations
| id | status    | created_at          |
|  1 | Opened    | 2019-11-12 11:46:11 |
|  1 | Completed | 2019-11-19 23:03:24 |
|  1 | Pending   | 2019-11-15 12:04:13 |
|  2 | Opened    | 2019-11-14 11:46:11 |
|  2 | Completed | 2019-11-20 23:03:24 |
|  2 | Pending   | 2019-11-17 12:04:13 |

我也有一张桌子，每个日历日从2019-11-01到2019-12-31。

我需要找出在上述时间段内每个日历日存在每种状态的次数。

如果状态在2019-12-14为打开，在2019-12-17为待处理，我需要计算一下从2019-12开始每天的状态为打开- 14至2019-12-17。

理想：

|2019-11-12 00:00:00 | Opened    | 1 |
|2019-11-12 00:00:00 | Pending   | 0 |
|2019-11-12 00:00:00 | Completed | 0 |
|2019-11-13 00:00:00 | Opened    | 1 |
|2019-11-13 00:00:00 | Pending   | 0 |
|2019-11-13 00:00:00 | Completed | 0 |
|2019-11-14 00:00:00 | Opened    | 2 |
|2019-11-14 00:00:00 | Pending   | 0 |
|2019-11-14 00:00:00 | Completed | 0 |
|2019-11-15 00:00:00 | Opened    | 1 |
|2019-11-15 00:00:00 | Pending   | 1 |
|2019-11-15 00:00:00 | Completed | 0 |

非常感谢您的帮助。

Answer 1

我会这样：获取每个ID的每个状态的开始和结束，使用表格在2019年11月1日至2019年12月31日之间的每个日历日计算发生次数，并按状态和日期进行基本计数

with Reservations cte as 
(
 select 
 a.id, a.status, a.created_at::date, 
 LAG(a.created_at::date, 1,0) OVER (PARTITION BY YEAR(a.id) ORDER BY YEAR(a.created_at)) 
 AS Ended_at
 Reservations a 
)
Select b.day, status, count(*)  
from Reservations a inner join calendar b on b.day >= created_at and
b.day < Ended_at       
group by b.day, status