Find active transactions in db - oracle database script

col name format a10 col username format a8 col osuser format a8 col start_time format a17 col status format a12 tti 'Active transactions'
SELECT s.sid,
       username,
       t.start_time,
       r.name,
       t.used_ublk "USED BLKS",
       decode(t.space, 'YES', 'SPACE TX', decode(t.recursive, 'YES', 'RECURSIVE TX', decode(t.noundo, 'YES', 'NO UNDO TX', t.status))) status
FROM sys.v_$TRANSACTION t,
                        sys.v_$rollname r,
                               sys.v_$SESSION s
WHERE t.xidusn = r.usn
  AND t.ses_addr = s.saddr /