select now();
----------------------------
now |
----------------------------
2020-04-03 10:33:07.540098+08
select current_time;
----------------------------
current_time |
----------------------------
10:35:13.165315+08
select current_date;
----------------------------
current_date |
----------------------------
2020-04-03
select date_part('day',CURRENT_DATE - cast('2019-06-23' as TIMESTAMP));
-----------
date_part
-----------
285