sysdate与long类型互转

select sysdate, 
(sysdate- to_date('1970-01-01','yyyy-mm-dd'))* 24*60*60*1000
current_milli from dual;

--2011-10-27 11:21:55
select   to_date('1970-01-01 00:00:00','yyyy-mm-dd hh24:mi:ss')
+   1319714515000/1000/24/60/60  from   dual