--获取当前的SCN
select dbms_flashback.get_system_change_number scn1,timestamp_to_scn(sysdate) scn2 from dual;

--将SCN转换成功时间
select to_char(scn_to_timestamp(34607271), 'yyyy-mm-dd hh24:mi:ss') chr,
       timestamp_to_scn(scn_to_timestamp(34607271)) dt
  from dual;