How to change the Oracle Character Set

Sqlplus/nolog
Conn/As sysdba
Shutdown immediate;
Startup Mount;
Alter session set SQL _trace = true;
Alter system enable restricted session;
Alter system set job_queue_processes = 0;
Alter system set aq_tm_processes = 0;
Alter database open;
Set linesize 120;
Alter database character set zhs16gbk;

Rror at line 1:

ORA-12712: new character set must be a superset of old Character Set

Alter database character set internal_use zhs16gbk;

Alter session set SQL _trace = false;

Shutdown immediate;

Startup

 

Select userenv ('language') from dual;