Oracle-L: RE: Of CLOB's, multi-byte characters and NCLOB's...

From: DENNIS WILLIAMS <DWILLIAMS_at_LIFETOUCH.COM>
Date: Tue, 06 May 2003 06:02:22 -0800
Message-ID: <F001.00590E0F.20030506060222@fatcity.com>

Steve

I just love inconsistent documentation:

stores single-byte character data
Both fixed-width and variable-width I want to know how you can have a variable-width character that occupies a single byte? This explains why I could never figure out NLS. It doesn't make sense! Fortunately I've never really had to outside the exams.

Dennis Williams
DBA, 60%OCP, 100% DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
Sent: Monday, May 05, 2003 7:32 PM
To: Multiple recipients of list ORACLE-L

Here's a copy/paste from the Oracle docs on CLOB's and NCLOBS.

CLOB Datatype
The CLOB datatype stores single-byte character data. Both fixed-width and variable-width character sets are supported, and both use the CHAR database character set. CLOBs can store up to 4 gigabytes of character data.

NCLOB Datatype
The NCLOB datatype stores multibyte national character set character (NCHAR) data. Both fixed-width and variable-width character sets are supported. NCLOBs can store up to 4 gigabytes of character text data.

The docs make it sound like CLOB's only store single-byte data and not multi-byte data. On a UTF8 database we were able to store Japanese kanji in a column of type CLOB. In a browser the kanji displays as kanji according to our session NLS settings. (Pardon my apparent xenophobia but they just look like chicken scratchings to me ;-)

-----Original Message-----
Sent: Monday, May 05, 2003 3:52 PM
To: Multiple recipients of list ORACLE-L

Steve

I don't understand this at all, but I happened to be reading on this, and I think the difference is between the "Database Character Set" and the "National Character Set". CLOB works with the Database Character Set and NCLOB works with the National Character Set. If at database creation time you don't specify a National Character Set, it defaults to your Database Character Set. Someone earlier posted the following query on this list: select name, substr(value$,1,20) from sys.props$ This displays all your NLS stuff for your database. Okay, we have now exceeded what I know about this subject, and hopefully someone on this list that actually understands the multi-byte character sets will provide a further explanation.

Dennis Williams
DBA, 60%OCP, 100% DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
Sent: Monday, May 05, 2003 2:22 PM
To: Multiple recipients of list ORACLE-L

We have several columns of datatype CLOB and one of our developers says we can store multi-byte characters in Oracle CLOB columns because multi-byte characters are just a few single-byte characters strung together. Sure enough, using OCI our app displays multi-byte Kanji characters just fine. Interesting! So that being the case, what's the difference between CLOB's and NCLOB's? If CLOB's work just fine for storing multi-byte characters then why even bother with NCLOB's? Even though our app has been working just fine by storing multi-byte characters in CLOB's, are there any potential gotchas?

Still trying to get back into productive work after IOUG...

Steve Orr
Bozeman, Montana
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Author: Orr, Steve
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Author: DENNIS WILLIAMS
INET: DWILLIAMS_at_LIFETOUCH.COM

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Author: Orr, Steve
INET: sorr_at_rightnow.com

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