Question

我有一列“ customer_date”，其数据类型为文本。

基于我需要派出新列的时间

条件：

customer_date <12时为'AM'，否则为'PM

customer_date

01Mar2018 10:03:54
02Mar2018 13:03:54

预期产量

  customer_date             session

01Mar2018 10:03:54        AM
02Mar2018 13:03:54        PM

我写

时抛出错误

select 
case EXTRACT(HOUR FROM customer_date)<12 then 'AM' else 'PM' end as session
from my table;

Answer 1

这在我测试时有效：

select (case when EXTRACT(HOUR FROM customer_date::timestamp) < 12 then 'AM' else 'PM' end) as session
from mytable;

我添加了显式转换和when。

Answer 2

您忘了像{Gordon Linoff所说的那样，在WHEN中添加CASE WHEN。

有一种简单的方法，使用TO_CHAR代替CASE WHEN。

习惯TO_CHAR

AM, am, PM or pm将获得子午线指示器（无期限）

CREATE TABLE myTable(customer_Date timestamp);

insert into myTable values ('01Mar2018 10:03:54'::timestamp);

insert into myTable values ('02Mar2018 13:03:54'::timestamp);

查询1 ：

select customer_Date,TO_CHAR(customer_Date::timestamp, 'AM') as session
from mytable

Results ：

|        customer_date | session |
|----------------------|---------|
| 2018-03-01T10:03:54Z |      AM |
| 2018-03-02T13:03:54Z |      PM |

根据时间戳导出新列

2 个答案: