postgresql 基于秒的 Postregsql 日期差异
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Postregsql Date Difference on basis on seconds
提问by Satish Sharma
How can I find date difference between two dates in terms of seconds in PostgreSQL?
如何在 PostgreSQL 中以秒为单位找到两个日期之间的日期差异？
There is no function for giving date difference in terms of seconds like in SQL-Server:
没有像 SQL-Server 那样以秒为单位给出日期差异的功能：
DATE_DIFF(second, '2011-12-30 09:55:56', '2011-12-30 08:54:55')
Please help me to have this in PostgreSQL too
请帮我在 PostgreSQL 中也有这个
回答by araqnid
First, the dates need to be values of timestamptype (so append ::timestampif you're just specifying them as string literals).
首先，日期必须是timestamp类型值（::timestamp如果您只是将它们指定为字符串文字，则附加）。
If you subtract two timestamps, the result is of intervaltype, which describes a duration of time (in hours, minutes, seconds etc.) You can use extract(epoch from interval_value)to convert the interval into an absolute number of seconds.
如果减去两个时间戳，则结果是interval描述持续时间（以小时、分钟、秒等为单位）的类型。您可以使用extract(epoch from interval_value)将间隔转换为绝对秒数。
So, putting that all together:
所以，把所有这些放在一起：
select extract(epoch from ('2011-12-30 09:55:56'::timestamp - '2011-12-30 08:54:55'::timestamp));
Remember that the ::timestampis only needed to convert the string literal to a timestamp: you don't need it if you're using the value of a timestamp column, for example.
请记住，::timestamp仅需要将字符串文字转换为时间戳：例如，如果您使用时间戳列的值，则不需要它。
