一次oracle行级锁导致的问题

select a.username,a.sid,a.serial#,a.logon_time
from v$locked_object b,v$session a
where b.session_id=a.sid order by a.logon_time;

SELECT s.sid, s.serial#, s.username, s.schemaname, s.osuser, s.process, s.machine,
s.terminal, s.logon_time, l.type
FROM v$session s, v$lock l
WHERE s.sid = l.sid
AND s.username IS NOT NULL
ORDER BY sid;