Re: bytes vs chars

From: Hans Forbrich <fuzzy.graybeard_at_gmail.com>
Date: Fri, 11 Mar 2016 10:14:27 -0700
Message-ID: <56E2FCF3.6070100_at_gmail.com>

No. You are interpreting that parameter incorrectly.

http://docs.oracle.com/database/121/REFRN/GUID-221B0A5E-A17A-4CBC-8309-3A79508466F9.htm#REFRN10124

http://docs.oracle.com/database/121/NLSPG/ch2charset.htm#NLSPG170

Length semantics = Byte says "when I define a column as "col-name VARCHAR2(x)", the x is taken in bytes, regardless of character set. So "MyCOL VARCHAR2(20)" in byte semantics could be five to 20 characters (maximum) of storage allocated. If each character was unicode and used 4 bytes, all you could store is 5 characters.

You still want to find out the actual character set: http://docs.oracle.com/database/121/REFRN/GUID-3BCC0324-8FEC-409F-8472-74A72FDE310F.htm#REFRN30159

/Hans

On 11/03/2016 9:55 AM, Zelli, Brian wrote:
> So if nls_length_semantics is set to byte, can I assume the 1 char = 1 byte rule?
>
>
> Brian
>
>
>
> -----Original Message-----
> From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Hans Forbrich
> Sent: Friday, March 11, 2016 11:48 AM
> To: oracle-l_at_freelists.org
> Subject: Re: bytes vs chars
>
> I think the sentiment is correct, but there is a minor correction to the
> wording:
>
> Unicode is an attempt to get all different character sets into one
> superset, and is multi-byte in nature. The AL32UTF8 encoding for
> Unicode allows a character to be represented in the fewest required of 1, 2, 3 or 4 bytes, based on the Quick Link 'Code Charts' at http://unicode.org/
>
> The 1 character = 1 byte group are often known as 'single byte character sets' or 'single byte encoding'. These include ASCII and various ISO
> 8859 sets. A handy reference is at
> http://docs.oracle.com/database/121/NLSPG/ch2charset.htm#NLSPG166
>
> Therefore, I think the statement should be corrected to
>
> "If you're using a single-byte characterset then 1character = 1 byte.
> But if you're using a multibyte Unicode characterset then a character can be coded on several bytes."
>
> /Hans
>
> On 11/03/2016 8:50 AM, Ahmed Aangour wrote:
>> Hi,
>>
>> If you're using a unicode characterset then 1character = 1 byte. But
>> if you're using a multibyte characterset then a character can be coded
>> on several bytes.
>> You can check the character set of the database by querying
>> nls_database_parameters.
>>
>>
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Received on Fri Mar 11 2016 - 18:14:27 CET