以Postgresql为主,再聊聊资料库 有趣的日光节约时间

aki[aki]#* show timezone;+-------------+|  TimeZone   |+-------------+| Asia/Taipei |+-------------+(1 row)select '2020-03-07 00:00:00'::timestamptz + '2 days';+------------------------+|        ?column?        |+------------------------+| 2020-03-09 00:00:00+08 |+------------------------+select '2020-03-07 00:00:00'::timestamptz + '48 hours';+------------------------+|        ?column?        |+------------------------+| 2020-03-09 00:00:00+08 |+------------------------+set timezone='America/New_York';select '2020-03-07 00:00:00'::timestamptz + '2 days';+------------------------+|        ?column?        |+------------------------+| 2020-03-09 00:00:00-04 |+------------------------+select '2020-03-07 00:00:00'::timestamptz + '48 hours';+------------------------+|        ?column?        |+------------------------+| 2020-03-09 01:00:00-04 |+------------------------+-- Daylight Saving Timehttps://www.timeanddate.com/time/change/usahttps://udn.com/news/story/6813/4399368select '2020-03-07 22:00:00'::timestamptz + interval '1 hour' * n as "by hour"     , '2020-03-08 01:58:00'::timestamptz + interval '1 minute' * n as "by minute"     , '2020-03-08 01:59:58'::timestamptz + interval '1 second' * n as "by second"  from generate_series(1, 5) as n;+------------------------+------------------------+------------------------+|        by hour         |       by minute        |       by second        |+------------------------+------------------------+------------------------+| 2020-03-07 23:00:00-05 | 2020-03-08 01:59:00-05 | 2020-03-08 01:59:59-05 || 2020-03-08 00:00:00-05 | 2020-03-08 03:00:00-04 | 2020-03-08 03:00:00-04 || 2020-03-08 01:00:00-05 | 2020-03-08 03:01:00-04 | 2020-03-08 03:00:01-04 || 2020-03-08 03:00:00-04 | 2020-03-08 03:02:00-04 | 2020-03-08 03:00:02-04 || 2020-03-08 04:00:00-04 | 2020-03-08 03:03:00-04 | 2020-03-08 03:00:03-04 |+------------------------+------------------------+------------------------+(5 rows)可以观察到微妙的变化,特别注意到时区与UTC的差距 -05 变成 -04 了.