有时候操作数据库会被锁掉，表现就是对表操作的时候没有任何反应。
解锁的方法如下。重复下面的三个sql

SQL>  select sid from v$lock where block=1;

       SID
----------
        20

SQL> select sid,serial# from v$session where sid=20;

       SID    SERIAL#
---------- ----------
        20       2649

SQL> alter system kill session '20,2649';

System altered.

只到没有block=1的sid

SQL> select sid from v$lock where block=1;

no rows selected

感谢wxx

另一个查锁的sql

select l.sid,
       s.username,
       decode(l.type, 'TM', 'TABLE   LOCK', 'TX', 'ROW   LOCK', NULL) LOCK_LEVEL,
       o.owner,
       o.object_name,
       o.object_type,
       s.terminal,
       s.machine,
       s.program,
       s.osuser
  from v$session s, v$lock l, dba_objects o
 where s.sid = l.sid
   and o.object_id = l.id1
   and s.username is not null