Postgre SQL date_trunc() 和timestamp

01.SELECT now()::timestamp + '1 year';
02.SELECT now()::timestamp + '1 month';
03.SELECT now()::timestamp + '1 day';
04.SELECT now()::timestamp + '1 hour';
05.SELECT now()::timestamp + '1 min';
06.SELECT now()::timestamp + '1 sec';
07.select now()::timestamp + '1 year 1 month 1 day 1 hour 1 min 1 sec';
08.SELECT now()::timestamp + (col || ' day')::interval FROM table

select date_trunc('month',now()) +interval '12 h';    
//每月1号 12点    
select date_trunc('month',now()) + interval '15 d 9 h 30 min';    
//每月15号9点半    
select date_trunc('day',now()) + interval '9 h';    
//每天9点    
select date_trunc('day',now()) + interval '7 d';    
//每周的今天   
select date_trunc('weak',now())  + interval '1d 1minute';   
//每周的周二第一分钟   
select date_trunc('h',now()) + interval '30 minute';    
//每小时   
select date_trunc('minute',now()) + interval '30 second';   
//每分钟   
select date_trunc('minute',now()) + interval '30 minute 30 second';   
//每30分钟       
select date_trunc('quarter',now()) + interval '15 d 15 h 15 minute 30 second';    
//本季度的第15天,15小时 15分 30秒   
select date_trunc('quarter',now() ) - interval '1 h';   
//每个季度最后一天的晚上11点    
select date_trunc('quarter',now() + interval '3 month') - interval '1 h';   
//每个季度的最后一天的晚上的11点(从下个季度开始算起).