Postgresql Interval 转成秒

1、select EXTRACT(EPOCH FROM (now() - fg_last_retrive_time)) as diff,fg_last_retrive_status from tg_reader where fg_reader_ip ='128.31.188.46' ;

2、select date_part('epoch',(now() - fg_last_retrive_time),fg_last_retrive_status from tg_reader where fg_reader_ip ='128.31.188.46' ;