FreeTDS Development Group

["Jackson, Craig (Gale)" <Craig.Jackson AT cengage.com>]

I believe that the real issue is in the protocol spec and the databases.

Sybase, in particular, does not distinguish zero-length strings from NULLs in 
the database.

Is there an expectation that they would be stored differently?

Craig 

-----Original Message-----
From: freetds-bounces AT lists.ibiblio.org 
[mailto:freetds-bounces AT lists.ibiblio.org] On Behalf Of Damien Churchill
Sent: Monday, May 10, 2010 6:21 AM
To: avictor.za AT gmail.com
Cc: FreeTDS Development Group
Subject: Re: [freetds] Empty string in db-lib

On 10 May 2010 08:22, avictor.za AT gmail.com <avictor.za AT gmail.com> wrote:
> hi,
>
>>>> Is it possible to send an empty string as a parameter when making rpc
>>>> calls? All my efforts so far seem to result in the parameter ending up
>>>> being NULL when doing a trace on the server!
>>>
>>> It works.  Cf. src/dblib/unittests/rpc.c.
>
>>> According to Sybase, "If the value of the RPC parameter is NULL, pass
>>> datalen as 0, even if type is a fixed-length datatype."  That's what the
>>> unit test does, and the server recognizes them as NULL.
>
>> >From that it looks like it isn't possible to just send an empty string
>> '' which of course is different to NULL? Is this a limitation of
>> db-lib or the TDS protocol?
>
> We had the same issue with CTLib.
> Search mailing-list archive for "FreeTDS always setting empty
> VARCHAR's to NULL" (24 May 2009).
>
> A similar fix might be required for dblib.
>
>

Ahh excellent, I will have to investigate this a bit further once I
have my machine back up and running! Thanks for pointing me in the
right direction!

Damien
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