确定oracle 锁的有关问题

确定oracle 锁的问题
SELECT /*+ordered*/ b.USERNAME,b.SERIAL#,d.ID1,a.SQL_TEXT
FROM v$lock d,V$session b, v$sqltext a
WHERE b.LOCKWAIT = d.KADDR
  AND a.ADDRESS = b.SQL_ADDRESS
  AND a.HASH_VALUE = b.SQL_HASH_VALUE;