select current_timestamp,current_date,current_time,now()/3,now() / time '04:20 ago',timeofday();

insert into test_tbl values(

'tomorrow','now' /5,'yestday','current');

위에서처럼 어떤건 insert때만 동작하는것 같아요

select date_part( 'hour',now() );

select date_trunc( 'minuate',now());

select ago( now()/5,now());