RE: Diff NLS_CHARACTERSET & NLS_NCHAR_CHARACTERSET

RE: Diff NLS_CHARACTERSET & NLS_NCHAR_CHARACTERSET

 

  

Hi Cave and All

In our current 9i database we have the following character set values:

NLS_CHARACTERSET WE8ISO8859P1
NLS_NCHAR_CHARACTERSET AL16UTF16


We had imported 8i database dump into the 9i database. We understand
that AL16UTF16 is a Unicode based character set. In our case as
mentioned above NLS_NCHAR_CHARACTERSET is AL16UTF16

The following doubts I have in my mind.

1) Is it necessary to have NLS_CHARACTERSET to in Unicode before
importing.
2) Will there be a problem later on in the data because the
NLS_NCHAR_CHARACTERSET is AL16UTF16 and NLS_CHARACTERSET is
WE8ISO8859P1.
3) Could we go ahead now with above settings and alter the
NLS_NCHAR_CHARACTERSET to WE8ISO8859P1 (Hope this not meaningful to
change).
4) What could be the settings before import and after import for both
character sets?

Your immediate advice will be greatly appreciated.

Regs,
Sree

-----Original Message-----
From: Justin Cave (DDBC)
[mailto:oracledba-ezmlmshield-x75664443.[Email address protected]
Sent: Wednesday, May 04, 2005 1:46 PM
To: LazyDBA Discussion
Subject: RE: Diff NLS_CHARACTERSET & NLS_NCHAR_CHARACTERSET

There is no such thing as a corresponding character set. Any valid
national character set might be a reasonable choice given any database
character set.

Do you want to store characters that are not in the ISO 8859-1 character
set in your database? If not, you presumably will not be creating any
tables with NCHAR or NVARCHAR2 columns, so your National character set
would be completely irrelevant. If you do want to store characters that
are not in the ISO 8859-1 character set, what sorts of characters do you
want to store?

Justin Cave
Distributed Database Consulting, Inc.
http://www.ddbcinc.com/askDDBC

-----Original Message-----
From: Sreedhar_Bhaskararaju
[mailto:oracledba-ezmlmshield-x8687003.[Email address protected]
Sent: Wednesday, May 04, 2005 4:04 AM
To: LazyDBA Discussion
Subject: RE: Diff NLS_CHARACTERSET & NLS_NCHAR_CHARACTERSET

What is the corresponding NLS_NCHAR_CHARACTERSET to Western European
Character Set < WE8ISO8859P1 >?

Regs,
Sree

-----Original Message-----
From: Justin Cave (DDBC)
[mailto:oracledba-ezmlmshield-x21293310.[Email address protected]
Sent: Wednesday, May 04, 2005 1:25 PM
To: LazyDBA Discussion
Subject: RE: Diff NLS_CHARACTERSET & NLS_NCHAR_CHARACTERSET

The basic difference is that NLS_CHARACTERSET controls the character set
used to encode CHAR and VARCHAR2 columns while NLS_NCHAR_CHARACTERSET
controls the character set used to encode NCHAR and NVARCHAR2 columns.

If your database character set (NLS_CHARACTERSET) allows you to encode
all the characters your application needs or wants to encode, you would
normally ignore the national character set (NLS_NCHAR_CHARACTERSET)
because working with NCHAR and NVARCHAR2 data types tends to get
somewhat complex. Occasionally, you would choose a UTF16 National
character set in addition to a UTF8 database character set if you are
storing a lot of Asian characters and want to save on space (Asian
characters require 2-bytes in the UTF16 encoding and normally require 3
bytes in the UTF8 encoding) and are willing to make the trade-off for
more complexity.

National character sets also tend to come in to play in databases where
you cannot change the database character set and need to add support for
encoding characters that are not represented in the database character
set. In 9i and later, only the Unicode character sets are valid values
for the National character set.

Justin Cave
Distributed Database Consulting, Inc.
http://www.ddbcinc.com/askDDBC

-----Original Message-----
From: Sreedhar_Bhaskararaju
[mailto:oracledba-ezmlmshield-x25362953.[Email address protected]
Sent: Wednesday, May 04, 2005 3:42 AM
To: LazyDBA Discussion
Subject: Diff NLS_CHARACTERSET & NLS_NCHAR_CHARACTERSET

Hi All,



What is the relation between NLS_CHARACTERSET and
NLS_NCHAR_CHARACTERSET, How to choose NLS_NCHAR_CHARACTERSET for a given
NLS_CHARACTERSET.



Regs,

Sree



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