Re: [cx-oracle-users] varchar2 length > 250

[Kathryn M. <ka...@cs...>]

I don't have much experience with character sets, but here's what I was 
able to find out.

Server side:
--------------
NLS_LANG is not set.
NLS_DATABASE_PARAMETERS:
	NLS_LANGUAGE		AMERICAN
	NLS_TERRITORY		AMERICA
	NLS_CHARACTERSET	WE8ISO8859P1
 From my reading 
(http://www.oracle.com/technology/tech/globalization/htdocs/nls_lang%20faq.htm), 
I think that because NLS_LANG is not set, the default character encoding 
for database entries is AMERICAN_AMERICA.US7ASCII.

Client side:
-------------
NLS_LANG is not set.
 >>> import sys, locale
 >>> print locale.getdefaultlocale()
(None, None)
 >>> print sys.stdout.encoding
ANSI_X3.4-1968
I think that the oracle instant client uses the default values when 
NLS_LANG is not set (AMERICAN_AMERICA.US7ASCII).  I would think that 
this default encoding is compatible with the system encoding because 
they're both 7-bit ascii.

However, even though I think the encodings are compatible, retrieving 
the characters and printing them doesn't "just work." My suspicion is 
that the problem occurs because NLS_LANG is not set on the server side. 
I have not yet experimented with setting this though.

Any advice would be greatly appreciated.
Thanks,
Kathryn

Anthony Tuininga wrote:
> Hmm, I tried the steps you gave and did not get the same results. The
> possibility, however, is that the database character set and the
> client character set are not the same as the ones you've used. Perhaps
> you can detail that information as well? If it gets too much into the
> unicode side of things I won't be able to be much help but others
> might be able to help on that front.....
> 
> On 6/21/06, Kathryn Mohror <ka...@cs...> wrote:
>> Hi,
>>
>> I am trying to select and print strings from an Oracle 10.1.0.3.0
>> database using cx_Oracle 4.1.2 and python 2.4.2.
>>
>> The problem: If I insert strings into a VARCHAR2 field with > 250
>> characters, I get garbage when I retrieve them.
>>
>> Example test scenario:
>>
>> 1. in sqlplus, I execute the following commands:
>> create table temp_k (b varchar2(500 byte), c varchar2(500 char));
>> insert into temp_k (b,c) values (rpad('b',200,'b'),rpad('c',200,'c'));
>> commit;
>>
>> 2. Now I use cx_oracle to retrieve the strings:
>>      sql = "select b,c from temp_k"
>>      ptds.cursor.execute(sql)
>>      rets = ptds.cursor.fetchall()
>>      print ptds.cursor.description
>>      for b,c in rets:
>>          towrite = "byte:%s\n"% b
>>          f.write(towrite)
>>          towrite = "char:%s\n"% c
>>          f.write(towrite)
>>
>>     I get the output I expect.
>> [('B', <type 'cx_Oracle.STRING'>, 500, 500, 0, 0, 1), ('C', <type
>> 'cx_Oracle.STRING'>, 500, 500, 0, 0, 1)]
>> byte:bbbbbbbbbbbb <snip for space> up to 200
>> char:cccccccccccc <snip for space> up to 200
>>
>> 3. Now, in sqlplus, I execute:
>> insert into temp_k (b,c) values (rpad('h',251,'h'),rpad('i',251,'i'));
>> commit;
>>
>> 4. Now, from my python script using cx_oracle, I retrieve the strings as
>> in step #2. Now I get garbage for the last two rows:
>> byte:bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
>> char:cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
>> byte:hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh?^@uiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii
>> char:iiiii^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@
^@
>  ^
>> @^@^@^@^@^@
>>
>> If I insert more rows of length < 251 after step #4, those rows are also
>> returned as garbage. When I retrieve these strings via sqlplus or the QT
>> interface, I do not receive garbage.
>>
>> Do you know what is happening here?
>>
>> Thanks,
>> Kathryn
>>
>>
>>
>> _______________________________________________
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>>
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