FreeTDS Development Group

["Thompson, Bill D (London)" <ThompBil AT exchange.uk.ml.com>]

Small world!

I am actually in the process of doing a rework on the convert functionality
in FreeTDS.
There are a number of shortfalls in this, of which you've just spotted one.
I spotted the same issue as I was going through the code a couple hours ago!

have patience and it will be fixed....

Bill

> -----Original Message-----
> From: Paul Rensing [SMTP:paul.rensing AT att.net]
> Sent: Thursday, July 11, 2002 2:46 PM
> To:   TDS Development Group
> Subject:      [freetds] Bug converting NULL field in SQLBindCol?
> 
> Hi,
> 
> I am using FreeTDS as an ODBC driver talking to a SQLServer. This is under
> RedHat 7.3 with FreeTDS from about June 7 (one of the "current" versions).
> 
> My actual setup is to use Python and the mxODBC code talking to the
> unixODBC code. Everything works pretty well except there is a problem if
> the database entry is NULL (the column is typed as a float). When the DB
> has a NULL, the Python code gets back the previous value that was in that
> column; that is, it is referencing old, stale data.
> 
> The mxODBC code attempts to use SQLBindCol where possible. The problem
> appears to be that tds_convert() and its children (tds_convert_flt8() in
> this case) don't seem to check whether the NULL flag is set and thus clear
> the data field and length. mxODBC expects the length field to be set to
> SQL_NULL_DATA (which is -1 in sql.h).
> 
> So, where is the bug? I would be glad to help a little, but I am not very
> familiar with ODBC code. If someone can let me know what the right
> behaviour is, I can attempt a patch.
> 
> Thanks,
>           Paul Rensing
> 
> 
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