使用dba用户登录
1、查看当前服务器的字符集
select userenv('language') from dual; 
2、关闭数据库
shutdown immediate;
3、启动到Mount 
startup mount;
4、会话字符集的环境
select * from nls_session_parameters 
5、修改oracle的字符集 
ALTER SYSTEM SET JOB_QUEUE_PROCESSES=0; 
ALTER SYSTEM SET AQ_TM_PROCESSES=0; 
ALTER DATABASE OPEN; 
ALTER DATABASE NATIONAL CHARACTER SET INTERNAL_USE ZHS16GBK; 
SHUTDOWN IMMEDIATE; 
STARTUP;