ORACLE修改字符集

命令如下：

SQL> conn sys/sys as sysdba;
SQL> shutdown immediate;
SQL> STARTUP MOUNT;
SQL> ALTER SESSION SET SQL_TRACE=TRUE;
SQL> ALTER SYSTEM ENABLE RESTRICTED SESSION;
SQL> ALTER SYSTEM SET JOB_QUEUE_PROCESSES=0;
SQL> ALTER SYSTEM SET AQ_TM_PROCESSES=0;
SQL> Alter database open;
SQL> ALTER DATABASE CHARACTER SET ZHS16GBK;

ALTER DATABASE NATIONAL CHARACTER SET INTERNAL_USE UTF8;

ALTER DATABASE CHARACTER SET ZHS16GBK;出现错误？
注册表：
HEKY_LOCAL_MACHINE/SOFTWARE/ORACLE/nls_lang值修改为

SIMPLIFIED CHINESE_CHINA.ZHS16GBK