FreeTDS Development Group

["Paul Rensing" <paul.rensing AT att.net>]

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