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) minutes
from v$log_history a, v$log_history b
where a.RECID = b.recid+1
order by a.FIRST_TIME asc
