Character set modification of oracle database

To modify the character set on the server side, start the database in RESTRICTED mode to change the character set:

SQL> conn /as sysdba  
SQL> shutdown immediate;  
SQL> startup mount  
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 INTERNAL_USE ZHS16GBK;  
SQL> select * from v$nls_parameters;  
SQL> shutdown immediate;  
SQL> startup  
SQL> select * from v$nls_parameters;