SELECT '1-1-2014 02:00:00'::timestamp at time zone 'America/Los_Angeles';

回报

2014-01-01 02:00:00-08

–

SELECT CAST('1-1-2014 02:00:00'::timestamp at time zone 'America/Los_Angeles' AS Date);

回报

2014-01-01

但是我想要它返回2013-12-31

和

SELECT CAST('1-1-2014 00:02:00'::timestamp at time zone 'America/Los_Angeles' AS Date) at time zone 'America/Los_Angeles';

回报

2014-01-01 00:00:00

但我希望它返回2013-12-31 00:00:00

所以,我基本上想要在它所在的时区中返回日期,在这种情况下是太平洋时区.

SELECT '1-1-2014 02:00:00'::timestamp at time zone 'UTC' at time zone 'America/Los_Angeles';
      timezone       
---------------------
 2013-12-31 18:00:00