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how to know character set as single character or multi character [message #596750] Thu, 26 September 2013 02:36 Go to next message
ishika_20
Messages: 334
Registered: December 2006
Location: delhi
Senior Member
Dear All,

I would like to know, how do we know database character set is either single character set or multi character set?

While changing character-set from AL32UTF8 to WE8MSWIN1252 got  "ORA-12712: new character set must be a superset of old character set".

Below are steps taken to resolve the issue -

ALTER DATABASE CHARACTER SET WE8MSWIN1252;

i got this error: ORA-12712: new character set must be a superset of old character set

After some googling I found solution, below are the commands executed by me:

SQL> SHUTDOWN IMMEDIATE;
SQL> CONNECT SYS/password AS SYSDBA;
SQL> STARTUP MOUNT;
SQL> ALTER SYSTEM ENABLE RESTRICTED SESSION;
SQL> ALTER DATABASE OPEN;
SQL> ALTER DATABASE CHARACTER SET INTERNAL_USE WE8MSWIN1252;
SQL> SHUTDOWN;
SQL> STARTUP;
SQL> QUIT;

And its working...


I have not done it in proper order. Neither have done ccsscan.
Still, no user reported any issues. Do my changes truncated the data?

Regards,
Ishika
icon4.gif  Re: how to know character set as single character or multi character [message #596754 is a reply to message #596750] Thu, 26 September 2013 02:58 Go to previous messageGo to next message
Michel Cadot
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Quote:
ORA-12712: new character set must be a superset of old character set


Yes, hopefully, Oracle does not let you screw your database.

Quote:
ALTER DATABASE CHARACTER SET INTERNAL_USE WE8MSWIN1252;


Now you screwed your database!

Quote:
And its working...


No! it seems to have worked because Oracle did not return you an error BECAUSE you told it to NOT return an error; this is what INTERNAL_USE means and it also means you must NOT use it as it is ONLY for Oracle support.

Re: how to know character set as single character or multi character [message #596755 is a reply to message #596750] Thu, 26 September 2013 03:04 Go to previous messageGo to next message
Lalit Kumar B
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Location: Hi-tech city
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Related thread http://www.orafaq.com/forum/t/187940/0/

From the docs, Database characters sets

Regards,
Lalit

[Updated on: Thu, 26 September 2013 03:06]

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Re: how to know character set as single character or multi character [message #596756 is a reply to message #596755] Thu, 26 September 2013 03:09 Go to previous messageGo to next message
ramoradba
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If it possible for you ... Read this Meta link
Doc ID 260192.1
Note 179133.1
Note 264157.1


Sriram Sanka

[Updated on: Thu, 26 September 2013 03:12]

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Re: how to know character set as single character or multi character [message #596759 is a reply to message #596756] Thu, 26 September 2013 03:50 Go to previous messageGo to next message
ishika_20
Messages: 334
Registered: December 2006
Location: delhi
Senior Member
Thank you All.

Mr Michel, can you please clear my doubt?
As of now user didn't reported any problem as it is testing server. From now if they enter any data into it will not have any problem ..rite???

Regards,
Ishika
Re: how to know character set as single character or multi character [message #596763 is a reply to message #596759] Thu, 26 September 2013 04:29 Go to previous messageGo to next message
Lalit Kumar B
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AL32UTF8 and WE8MSWIN1252 are both ASCII Database Character Sets. And both are 8-bit. So, data should not change. If you change from 7-bit to 8-bit, an extra bit will be added. But you have used INTERNAL_USE which should be used only by Oracle suppport staff, so nobody can gurantee the consequences now. If you have any dump from previous character set, now check and see with dump for new data.

Regards,
Lalit
icon2.gif  Re: how to know character set as single character or multi character [message #596764 is a reply to message #596759] Thu, 26 September 2013 04:31 Go to previous messageGo to next message
Michel Cadot
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If ALL characters were/will be in US7ASCII then you might not have any problem as code points for AL32UTF8 and WE8MSWIN1252 are by chance the same ones in both character sets.



Re: how to know character set as single character or multi character [message #596771 is a reply to message #596764] Thu, 26 September 2013 05:08 Go to previous messageGo to next message
ishika_20
Messages: 334
Registered: December 2006
Location: delhi
Senior Member
Dear Lalit / Michel,

Thanks a lot.

Can you please provide me link to know which character set is of which bit ?
Is there and terms as multi-character and single character? or it is denoted by bit like 7-bit or 8-bit?

Regards,
Ishika
icon2.gif  Re: how to know character set as single character or multi character [message #596777 is a reply to message #596771] Thu, 26 September 2013 05:23 Go to previous messageGo to next message
Michel Cadot
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As of a rule of thumb:
US7... -> 7 bits
WE8... -> 8 bits
AL16... -> 16 bits
AL32... -> 32 bits (but AL32UTF8 is an exception as size of characters is varying from 1 to 4 bytes, and even in rare case 8 bytes)

icon3.gif  Re: how to know character set as single character or multi character [message #596780 is a reply to message #596777] Thu, 26 September 2013 05:27 Go to previous messageGo to next message
Michel Cadot
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See Database Globalization Support Guide
Chapter 2 Choosing a Character Set

Re: how to know character set as single character or multi character [message #596788 is a reply to message #596780] Thu, 26 September 2013 05:54 Go to previous message
ishika_20
Messages: 334
Registered: December 2006
Location: delhi
Senior Member
Thank you very much to you all.

I got it very nicely.

Regards,
Ishika
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