PostgreSQL：将时间戳转换为时间 - 或仅从时间戳列中检索时间
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PostgreSQL: Convert timestamp to time - or retrieve only time from timestamp column
提问by Lars Juel Jensen
What I want is something equivalent to this:
我想要的是相当于这个的东西：
select to_time( to_timestamp ( '03.04.2014 12:34:00', 'DD.MM.YYYY HH24:MI:SS' ) )
Problem here is that to_time does not exist. I want this to result in
这里的问题是 to_time 不存在。我希望这导致
12:34:00 (without the date)
Is this possible ?
这可能吗 ？
回答by a_horse_with_no_name
select timestamp '2014-04-03 12:34:00'::time
I prefer ANSI date/timestamp literals as they are shorter to write than to_timestamp()
我更喜欢 ANSI 日期/时间戳文字，因为它们比 to_timestamp()
The above is equivalent to:
以上等价于：
select to_timestamp ('03.04.2014 12:34:00', 'DD.MM.YYYY HH24:MI:SS')::time
the ::timeis Postgres' short hand notation for casting a value.
这::time是 Postgres 用于转换值的简写符号。
The following would be complete ANSI SQL if you want that:
如果需要，以下将是完整的 ANSI SQL：
select cast(timestamp '2014-04-03 12:34:00' as time)
