select to_char(systimestamp, 'yyyymmdd hh24:mi:ss.ff ') from dual;--20120516 11:56:40.729083
select to_char(systimestamp, 'yyyymmdd hh24:mi:ss.ff3 ') from dual;--20120516 11:58:42.755
select to_char(sysdate,'yyyy-MM-dd HH24:mi:ss') from dual;
select to_char(systimestamp, 'yyyymmdd hh24:mi:ss.ff3 ') from dual;--20120516 11:58:42.755