如何在 PostgreSQL 中截断日期？
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How to truncate date in PostgreSQL?
提问by yegor256
I'm trying to select all transactions in PostgreSQL 9 that happened earlier than the end of the last week. Which date function I should use to build such an interval?
我正在尝试选择 PostgreSQL 9 中发生在上周末之前的所有事务。我应该使用哪个日期函数来构建这样的间隔？
回答by regilero
> select now();
"2013-09-09 11:43:29.307089+02"
> select date_trunc('week',now()-'1 week'::interval);
"2013-09-02 00:00:00+02" //start of previous week
> select date_trunc('week',now())
"2013-09-09 00:00:00+02" // start of current week
> select date_trunc('week',now())-'1 s'::interval;
"2013-09-08 23:59:59+02" // end of previous week
So using date_trunc('week',now())-'1 s'::interval;on the right side of your date operator should work. This is a timestamp with time zone value which refers in fact to 23:59:59 on sunday, but with 2 hours of difference with UTC time, depends on your locale and settings.
因此date_trunc('week',now())-'1 s'::interval;，在日期运算符的右侧使用应该可以工作。这是一个带有时区值的时间戳，实际上是指星期日的 23:59:59，但与 UTC 时间有 2 小时的差异，这取决于您的语言环境和设置。
回答by Joe Taras
You can fix a date or remove days from current day.
您可以修复日期或从当前日期中删除天数。
Show this: are the date/time operators and functions present in Postgres
显示这一点：Postgres 中是否存在日期/时间运算符和函数
I linked 9.1 functions because you've tagged with postgres 9.1, exists too the 9.2 reference page
我链接了 9.1 函数，因为你已经用 postgres 9.1 标记，也存在 9.2 参考页面
