postgresql Now() 没有时区
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Now() without timezone
提问by アレックス
I have a column added_atof type timestamp without time zone. I want it's default value to be the current date-time but without time zone. The function now()returns a timezone as well.
我有一个added_at类型的列timestamp without time zone。我希望它的默认值是当前日期时间但没有时区。该函数也now()返回一个时区。
How do I solve that problem?
我该如何解决这个问题？
回答by Erwin Brandstetter
SELECT now()::timestamp
That's all. The cast converts the timestamp to the current timestamp of your time zone. That's also how the standard SQL function LOCALTIMESTAMPis implemented in Postgres.
就这样。演员表将时间戳转换为您所在时区的当前时间戳。这也是标准 SQL 函数LOCALTIMESTAMP在 Postgres 中的实现方式。
If you don't operate in multiple time zones, that works just fine. Else switch to timestamptzfor added_at. The difference?
如果您不在多个时区操作，那效果很好。否则切换到timestamptzfor added_at。区别？
回答by Richard Huxton
Well you can do something like:
好吧，您可以执行以下操作：
SELECT now() AT TIME ZONE current_setting('TimeZone');
SELECT now() AT TIME ZONE 'Europe/Paris';
SELECT now() AT TIME ZONE 'UTC';
Not sure how that makes any sense for a column "added_at". You almost always want an absolute timestamp (timestamp with time zone) not a floating one.
不确定这对“ added_at”列有何意义。您几乎总是想要一个绝对时间戳（带时区的时间戳）而不是浮动时间戳。
Edit responding to points below:
编辑回应以下几点：
Yes, should use timestamp with time zone (absolute time) unless you have a good reason not to.
The client timezone is given by
SHOW TimeZoneorcurrent_setting(...)as shown above.
是的，除非您有充分的理由不这样做，否则应该使用带时区（绝对时间）的时间戳。
客户端时区由
SHOW TimeZone或给出，current_setting(...)如上所示。
Do take some time to skim the manuals - they cover all this quite well.
一定要花一些时间浏览手册——它们很好地涵盖了所有这些。
回答by Milen A. Radev
CURRENT_TIME and CURRENT_TIMESTAMP deliver values with time zone; LOCALTIME and LOCALTIMESTAMP deliver values without time zone.
CURRENT_TIME 和 CURRENT_TIMESTAMP 提供带时区的值；LOCALTIME 和 LOCALTIMESTAMP 提供没有时区的值。
