PostgreSQL 在滞后函数后为缺失的单元格添加特定值

Question

如果我运行查询：

SELECT status,
       created_at,
       lead(created_at) over(partition BY id
                             ORDER BY updated_at) ended_at
FROM salesdb.orders

我得到以下结果：

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

我想在缺失的单元格中插入一个特定的结束日期，如 '2019-12-31'

像这样：

| status    | created_at          | ended_at            |
| Opened    | 2019-11-12 11:46:11 | 2019-11-15 12:04:13 |
| Pending   | 2019-11-15 12:04:13 | 2019-11-19 23:03:24 |
| Completed | 2019-11-19 23:03:24 | 2019-12-31 00:00:00 |
| Opened    | 2019-11-14 11:46:11 | 2019-11-17 12:04:13 |
| Pending   | 2019-11-17 12:04:13 | 2019-11-20 23:03:24 |
| Completed | 2019-11-20 23:03:24 | 2019-12-31 00:00:00 |

Answer 1

使用lead()的三参数形式：

SELECT status,
       created_at,
       lead(created_at, 1, '2019-12-31') over (partition BY id
                                               order by updated_at
                                              ) as ended_at
FROM salesdb.orders

Answer 2

你也可以使用coalesce:

select status,
       created_at,
       coalesce(
           lead(created_at) over(partition by id order by updated_at), 
           '2019-12-31') ended_at
from salesdb.orders

PostgreSQL 在滞后函数后为缺失的单元格添加特定值

PostgreSQL adding specific value to missing cells after lag function

sql

database

postgresql

lag

coalesce