處理時間時用到了，記錄一下。

時間差天數(shù)

select ‘2017-12-10’::date – ‘2017-12-01’::date;

時間差秒數(shù)

select extract(epoch FROM (now() – (now()-interval ‘1 day’) ));
select trunc(extract(epoch FROM (now() – (now()-interval ‘1 day’) ))::numeric);
select trunc(extract(epoch FROM (now() – (now()-interval ‘1 day’) ))::numeric,1);
select round(extract(epoch FROM (now() – (now()-interval ‘1 day’) ))::numeric);
select round(extract(epoch FROM (now() – (now()-interval ‘1 day’) ))::numeric,1);