如何从postgres中的timestamp列获取日期或年份编号

Question

我在postgres上的表中有一个Timestamp列

CreatedAt

2016-10-26 07:33:51.029
2016-11-01 08:39:12.322

我需要得到一天的感觉

SELECT day number or may be month number 
FROM "MyTable";

预期产量将是

day

26
01

Answer 1

使用extract()函数：

select extract(day from createdat) as day,
       extract(year from createdat) as year
from "MyTable";

手册中的更多细节： https ： //www.postgresql.org/docs/current/static/functions-datetime.html#FUNCTIONS-DATETIME-EXTRACT

Answer 2

你可以试试

SELECT to_char("your column",'DD') as "day" 
FROM "MyTable";

更多信息， 请访问https://www.postgresql.org/docs/current/static/functions-formatting.html