判断Oracle的两个Undo日志之间的时间间隔

select b.RECID, to_char(b.FIRST_TIME, 'dd-mon-yy hh:mi:ss') start_time, a.RECID, to_char(a.FIRST_TIME, 'dd-mon-yy hh:mi:ss') end_time, ;round(((a.FIRST_TIME-b.FIRST_TIME)*24)*60,2) minutesfrom v$log_history a, v$log_history bwhere a.RECID = b.recid+1order by a.FIRST_TIME asc