select t2.username,t2.sid,t2.serial#,t2.@R_404_395@n_time
from v$locked_object t1,v$session t2
where t1.session_id=t2.sid order by t2.@R_404_395@n_time;
select
(select username from v$session where sid=a.sid) blocker,
a.sid,' is blocking ',
(select username from v$session where sid=b.sid) blockee,
b.sid
from v$lock a,v$lock b
where a.block=1 and b.request>0 and a.id1=b.id1 and a.id2=b.id2;