CPU usage

select

   ss.username,

   se.SID,

   VALUE/100 cpu_usage_seconds

from

   v$session ss,

   v$sesstat se,

   v$statname sn

where

   se.STATISTIC# = sn.STATISTIC#

and

   NAME like '%CPU used by this session%'

and

   se.SID = ss.SID

and

   ss.status='ACTIVE'

and

   ss.username is not null

order by VALUE desc;



Happy Learning..!!
Cheers..!!