Question

我有一张桌子，如下表

+----+----------------------------------+
| id |            Created_at            |
+----+----------------------------------+
|  1 | Monday 8 April 2019 8:30 AM      |
|  2 | Tuesday 9 April 2019 5:30 PM     |
|  3 | Wednesday 9 April 2019 8:30 PM   |
|  4 |  Thursday 10 April 2019 11:30 AM |
|  5 | Friday 11 April 2019 10:45 AM    |
+----+----------------------------------+

如何获得下表

+----+------------+
| id | Created_at |
+----+------------+
|  1 | 2019-04-08 |
|  2 | 2019-04-09 |
|  3 | 2019-04-09 |
|  4 | 2019-04-10 |
|  5 | 2019-04-11 |
+----+------------+

基本上我想将我的Created_at列转换为YYYY-MM-DD格式。

Answer 1

从示例数据中，您可以尝试使用::DATE

查询＃1

SELECT Created_at::DATE
FROM T;

| created_at               |
| ------------------------ |
| 2019-04-08T00:00:00.000Z |
| 2019-04-09T00:00:00.000Z |
| 2019-04-09T00:00:00.000Z |
| 2019-04-10T00:00:00.000Z |
| 2019-04-11T00:00:00.000Z |

View on DB Fiddle

Answer 2

PostgreSQL的日期/时间转换非常灵活，应该能够处理您的格式：

WITH
    data(Created_at) AS (VALUES
        ('Monday 8 April 2019 8:30 AM'),
        ('Tuesday 9 April 2019 5:30 PM'),
        ('Wednesday 9 April 2019 8:30 PM'),
        (' Thursday 10 April 2019 11:30 AM'),
        ('Friday 11 April 2019 10:45 AM ')
    )
SELECT trim(both from Created_at)::date AS Created_at
FROM data;

...导致：

 created_at 
------------
 2019-04-08
 2019-04-09
 2019-04-09
 2019-04-10
 2019-04-11
(5 rows)

在postgres中转换时间戳格式

2 个答案: