SQL 丢弃时间戳中的毫秒部分
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Discard millisecond part from timestamp
提问by Dipro Sen
How can I discard/round the millisecondpart, better if the secondpart is also removed from a timestampw/o timezone?
millisecond如果second零件也从timestampw/o 中取出，我该如何丢弃/环绕零件timezone？
回答by Erwin Brandstetter
A cast to timestamp(0)or timestamptz(0)roundsto full seconds:
转换为timestamp(0)或舍入到整秒：timestamptz(0)
SELECT now()::timestamp(0);
Fractions are not stored in table columns of this type.
分数不存储在这种类型的表列中。
date_trunc()truncates(leaves seconds unchanged) - which is often what you really want:
date_trunc()截断（保持秒数不变）——这通常是你真正想要的：
SELECT date_trunc('second', now()::timestamp);
回答by Yuriy Rypka
Discard milliseconds:
丢弃毫秒：
SELECT DATE_TRUNC('second', CURRENT_TIMESTAMP::timestamp);
2019-08-23 16:42:43
2019-08-23 16:42:43
Discard seconds:
丢弃秒数：
SELECT DATE_TRUNC('minute', CURRENT_TIMESTAMP::timestamp);
2019-08-23 16:42:00
2019-08-23 16:42:00
回答by Shriganesh Kolhe
if you just want time, here is the code for postgres
如果你只是想要时间，这里是 postgres 的代码
SELECT DATE_TRUNC('second', CURRENT_TIMESTAMP::timestamp)::time;
it will return 'time without time zone' data type
它将返回“没有时区的时间”数据类型
