168 - Change Oracle DB Chracter Set
If you want to change from WE8MSWIN1252 to AL32UTF8. Check the NLS parameters first.
SQL> SELECT PARAMETER, VALUE FROM NLS_DATABASE_PARAMETERS WHERE PARAMETER IN ('NLS_CHARACTERSET', 'NLS_NCHAR_CHARACTERSET'); |
The syntax of the ALTER DATABASE CHARACTER SET statement is as follows:
SQL> ALTER DATABASE [db_name] CHARACTER SET new_character_set; (db_name is an optional) |
For Example :
SQL> ALTER DATABASE CHARACTER SET AL32UTF8; |
To change the database character set, perform the following steps:
1. Shut down the database, using either a SHUTDOWN IMMEDIATE or a SHUTDOWN NORMAL statement.
2. Do a full backup of the database because the ALTER DATABASE CHARACTER SET statement cannot be rolled back.
3. Startup Oracle database
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 AL32UTF8; |
If you get the error ORA-12712, please update the following table.
"ORA-12712: new character set must be a superset of old character set"
SQL> update sys.props$ set VALUE$='AL32UTF8' where NAME='NLS_CHARACTERSET'; SQL> commit; |
If you get the error ORA-12721, please login as DBA user.
"ORA-12721: operation cannot execute when other sessions are active"
4. shutdown immediate; or shutdown normal;
5. startup oracle database
SQL> startup mount; SQL> shutdown immediate; SQL> SELECT PARAMETER, VALUE FROM NLS_DATABASE_PARAMETERS WHERE PARAMETER IN ('NLS_CHARACTERSET', 'NLS_NCHAR_CHARACTERSET'); |
------------------------------------------------------------------------------ MB : Multibyte Encoding |
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