Oracle 10 Gb modification of database Character Set

View Current Character Set

Reference
SQL> select * from nls_database_parameters where parameter like '% SET % ';

PARAMETER VALUE
----------------------------------------------------------------------
NLS_CHARACTERSET WE8ISO8859P1
NLS_NCHAR_CHARACTERSET AL16UTF16

Reference
SQL> select userenv ('language') from dual;

USERENV ('language ')
----------------------------------------------------
AMERICAN_AMERICA.WE8ISO8859P1

Try to modify character set directly

Reference
SQL> ALTER DATABASE CHARACTER SET ZHS16GBK;
Alter database character set ZHS16GBK
*
ERROR at line 1:
ORA-12712: new character set must be a superset of old character set

Use Oracle Internal commands to modify character sets (

Note: This process is only used for testing. We recommend using CSALTER in Oracle 10 Gb!
)

Reference
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.

Total System Global Area 167772160 bytes
Fixed Size 1218316 bytes
Variable Size 62916852 bytes
Database Buffers 100663296 bytes
Redo Buffers 2973696 bytes
Database mounted.
SQL> ALTER SYSTEM ENABLE RESTRICTED SESSION;

SQL> ALTER SYSTEM ENABLE RESTRICTED SESSION;

System altered.

SQL> ALTER SYSTEM SET JOB_QUEUE_PROCESSES = 0;

System altered.

SQL> ALTER SYSTEM SET AQ_TM_PROCESSES = 0;

System altered.

SQL> ALTER DATABASE OPEN;

Database altered.

SQL> ALTER DATABASE CHARACTER SET INTERNAL_USE zhs16gbk;

Database altered.

The alert Log is displayed at the time of modification:

Completed: ALTER DATABASE OPEN
Tue May 18 10:56:43 2010
Alter database character set INTERNAL_USE zhs16gbk
Tue May 18 10:56:47 2010
Updating character set in controlfile to ZHS16GBK
Synchronizing connection with database character set information
Refreshing type attributes with new character set information
Completed: alter database character set INTERNAL_USE zhs16gbk

View the modified result:

SQL> select * from nls_database_parameters where parameter like '% SET % ';

PARAMETER
------------------------------
VALUE
--------------------------------------------------------------------------------
NLS_CHARACTERSET
ZHS16GBK

NLS_NCHAR_CHARACTERSET
AL16UTF16

SQL> select userenv ('language') from dual;

USERENV ('language ')
----------------------------------------------------
AMERICAN_AMERICA.ZHS16GBK