如何更改Oracle 11g r2 Express版中的字符集

Question

I have to change the character set from AL32UTF8 to WE8MSWIN1252 in a Oracle 11g r2 Express instance... I tried to use the command:

ALTER DATABASE CHARACTER SET WE8MSWIN1252;

But it fails saying that MSWIN1252 isn't a superset of AL32UTF8. Then I found some articles talking about CSSCAN, and that tool doesn't seem to be available in Oracle 11 Express.

http://www.oracle-base.com/articles/10g/CharacterSetMigration.php

Anyone has an idea on how to do that? Thanks in advance

Edit Clarifying a little bit: The real issue is that I'm trying to import data into a table that has a column defined as VARCHAR(6 byte). The string causing the issue is 'eq.mês', it needs 6 bytes in MSWIN1252 and 7 bytes in UT8

Answer 1

You can't.

The Express Edition of 11g is only available using a UTF-8 character set. If you want to go back to the express edition of 10g, there was a Western European version that used the Windows-1252 character set. Unlike with the other editions, Oracle doesn't support the full range of character sets in the Express Edition nor does it support changing the character set of an existing XE database.

Why do you believe you need to change the database character set? Other than potentially taking a bit more storage space to support the characters in the upper half of the Windows-1252 range, which generally aren't particularly heavily used, there aren't many downsides to a UTF-8 database.

Answer 2

The problem of only execute that ALTER DATABASE command is that the Data Dictionary was not converted and it can be corrupted.

I had the same problem. In my case, we are using a Oracle 11g Express Edition (11.2.0.2.0) and we really need that it runs on WE8MSWIN1252 character set, but I cannot change the character set on installation (it always install with AL32UTF8).

With a Oracle Client 11g installed as Administrator and run only the csscan full=y (check this link https://oracle-base.com/articles/10g/character-set-migration ) and we notice that are lossy and convertible data problems in our database. But, the problems are with the MDSYS (Oracle Spatial) and APEX_040000 (Oracle Application Express) schemas. So, as we dont need this products, we remove them (check this link: http://fast-dba.blogspot.com.br/2014/04/how-to-remove-unwanted-components-from.html ).

Then, we export with expdp the users schemas and drop the users (they must be recreated at the end of the process).

Executing csscan again with full=y capture=y , it reports that: The data dictionary can be safely migrated using the CSALTER script . If the report doesnt have this, the csalter.plb script will not work, because there are some conditions that will not be satisfied:

• changeless for all CHAR VARCHAR2, and LONG data (Data Dictionary and Application Data)
• changeless for all Application Data CLOB
• changeless and/or convertible for all Data Dictionary CLOB

In our case, this conditions were satisfied and we could ran the CSALTER script successfully. Moreover, this script executes the ALTER DATABASE command you are trying to run and it converts the CLOB data of Data Dictionary that is convertible.

Finally, we create the users and the tablespaces of our application and we import the dump of the user data successfully.

Answer 3

I would say that your best option when you want to go to a character set that supports only a subset of the original characters, that your best option is to use exp and imp back (or expdp and impdp).

Are you sure that no single table will contain any character not found in the 1252 code page ?