postgresql 获取年、季、月、周、日、时、分、秒等数字

select now(); --当前时间 2021-04-21 11:36:56

SELECT EXTRACT (year FROM now()); --年 2021
SELECT EXTRACT (quarter FROM now()); --季 02
SELECT EXTRACT (month FROM now()); --月 04
SELECT EXTRACT (day FROM now()); --月中天 21
SELECT EXTRACT (week FROM now()); --周 16
SELECT EXTRACT (isodow FROM now()); --周中天 3
SELECT EXTRACT (hour FROM now()); --時 11
SELECT EXTRACT (minute FROM now()); --分 36
SELECT EXTRACT (second FROM now()); --秒 56.909161