问题
How can I discard/round the millisecond part, better if the second part is also removed from a timestamp w/o timezone ?
回答1:
A cast to timestamp(0) or timestamptz(0) rounds to full seconds:
SELECT now()::timestamp(0);
Fractions are not stored in table columns of this type.
date_trunc() truncates (leaves seconds unchanged) - which is often what you really want:
SELECT date_trunc('second', now()::timestamp);
回答2:
Discard milliseconds:
SELECT DATE_TRUNC('second', CURRENT_TIMESTAMP::timestamp);
2019-08-23 16:42:43
Discard seconds:
SELECT DATE_TRUNC('minute', CURRENT_TIMESTAMP::timestamp);
2019-08-23 16:42:00
来源：https://stackoverflow.com/questions/10213190/discard-millisecond-part-from-timestamp