Blocking Transactions

Show all transactions that have started more than an hour ago:

col username format a15
col name format a15
select s.username, s.sid, s.serial#, t.start_time, n.name
  from v$session s, v$transaction t, v$rollstat r, v$rollname n
  where s.saddr=t.ses_addr
  and r.usn=n.usn
  and to_date(t.start_time, 'MM/DD/YY HH24:MI:SS') < (SYSDATE-(1/24));