oracle ʱ¼ä²î

 //¼ÆËãºÁÃë²î(Á½¸ödateÀàÐ͵ÄÏà¼õΪÌìÊý²î±ð£¬È»ºóת»»ÎªºÁÃë)
select ceil(to_date('209-11-17 13:00:12','yyyy-mm-dd hh24:mi-ss')-to_date(2009-11-18 14:00:12','yyyy-mm-dd hh24:mi-ss') )from dual;
//¼ÆËãÏà²îÔ·Ý
select (EXTRACT(year from to_date('209-11-17','yyyy-mm-dd'))-EXTRACT(year from to_date('2009-11-18','yyyy-mm-dd') ))*12+(EXTRACT(month from to_date('209-11-17','yyyy-mm-dd'))-EXTRACT(month from to_date('2009-11-18','yyyy-mm-dd') )) from dual;
//ͨ¹ýʱ¼ä´ÁÔËËã
select to_timestamp('2009-11-17 19:20:12 234','yyyy-mm-dd hh24:mi:ss ff')-to_timestamp('2009-11-16 11:12:34 167','yyyy-mm-dd hh24:mi:ss ff') from dual;
·µ»ØֵΪ+000000010 00:02:24.00000000 ×Ö·û´®Òª×ª»»ÎªºÁÃëÊý×Ö£¬×Ô¶¨Ò庯ÊýʵÏÖ
//×Ô¶¨ÒåÓÃʱ¼ä´ÁÔËË㺯Êý
create or replace function TIME_INTERVAL(endTime varchar2,startTime varchar2)
  return number
IS
p_1 varchar2(40);
begin
p_1 := to_timestamp(endTime,'yyyy-mm-dd hh24:mi:ss ff')-to_timestamp(startTime,'yyyy-mm-dd hh24:mi:ss ff');
return trunc(to_number(substr((p_1),1,instr(p_1,' '))))*24*60*60+to_number(substr((p_1),instr((p_1),' ')+1,2))*60*60+to_number(substr((p_1),instr((p_1),' ')+4,2))*60+to_number(substr((p_1),instr((p_1),' ')+7,2));
end;