Oracle查询被锁定表以及解锁

在开发调试的时候，因为发生异常中途停止一个表的某条记录被我锁定了，执行更新语句的时候，一直更新不了，加上nowait马上返回错误ORA-00054: resource busy and acquire with NOWAIT specified。

select * from tbl_student where stu_no ='2016053100006517' for update 

SELECT object_name, machine, s.sid, s.serial#
  FROM gv$locked_object l, dba_objects o, gv$session s
 WHERE l.object_id¡¡ = o.object_id
   AND l.session_id = s.sid;

--alter system kill session 'sid, serial#'; 
ALTER system kill session '607, 23268';