[转帖]PG的时间函数使用整理如下

PG的时间函数使用整理如下

https://blog.csdn.net/dahuzix/article/details/48576945

 

1.获取系统时间函数 

select now(); –2012-05-12 18:51:59.562+08 
select current_timestamp; –2012-05-12 18:52:12.062+08 
select current_date; –2012-05-12 
select current_time; –18:53:23.234+08 

 

2.时间的计算 
–使用interval 

select now()+interval ‘2 day’; –2012-05-14 20:05:32.796+08 2天后 
select now()-interval ‘2 day’; –2012-05-10 20:07:23.265+08 2天前 
select now()+interval ‘2 hour’; –2012-05-12 22:06:38.375+08 2小时后 

 

….

interval可以不写，其值可以是 

Abbreviation Meaning 
Y Years 
M Months (in the date part) 
W Weeks 
D Days 
H Hours 
M Minutes (in the time part) 

 

3.时间的截取 

–使用extract extract(interval,timestamp); 
select extract(year from now()); –2012 
select extract(mon from now()); –5 5月份 
…

 

interval值参考上面 
4.时间的转换 

select timestamp ‘2012-05-12 18:54:54’; –2012-05-12 18:54:54 
select date ‘2012-05-12 18:54:54’; –2012-05-12 
select time ‘2012-05-12 18:54:54’; –18:54:54 
select TIMESTAMP WITH TIME ZONE ‘2012-05-12 18:54:54’ 
–2012-05-12 18:54:54+08

 

–与unix时间戳的转换 

SELECT TIMESTAMP ‘epoch’ + 1341174767 * INTERVAL ‘1 second’; 
–2012-07-01 20:32:47 

 

以上是基本的PG函数使用，可满足一般的开发运维应用