[python-sybase] Parameter passing with freetds/MSSQL2000

[Dave Cole]

> What is the current status regarding parameter passing with
> freetds/MSSQL2000? I get an error if I try simple queries.
> 
> import Sybase as dbapi
> 
> con=dbapi.connect('cazalla','gotta','password','personal')
> cur=con.cursor()
> cur.execute('select * from usuarios where cd_usuario=@u',  
> {'@u':'marcos'})
> pprint.pprint(cur.fetchall())
> 
> This is what I get (line numbers are incorrect)
> 
> Traceback (most recent call last):
>   File "etcPythonSybase.py", line 191, in ?
>     cur.execute('select * from usuarios where
> cd_usuario=@u',{'@u':'marcos'})
>   File "/usr/lib/python2.2/site-packages/Sybase.py", line 379, in
> execute
>     self._raise_error(Error, 'ct_param')
>   File "/usr/lib/python2.2/site-packages/Sybase.py", line 309, in
> _raise_error
>     raise exc(text)
> Sybase.Error: ct_param

I think it still has issues.  :-)

Looking at the FreeTDS 0.61 source for ct_param():

CS_RETCODE
ct_param(CS_COMMAND * cmd, CS_DATAFMT * datafmt, CS_VOID * data, CS_INT datalen, CS_SMALLINT indicator)
{
TDSSOCKET *tds;
TDSDYNAMIC *dyn;

/* TDSINPUTPARAM param; */

        tdsdump_log(TDS_DBG_FUNC, "%L inside ct_param()\n");
        tdsdump_log(TDS_DBG_INFO1, "%L ct_param() data addr = %d data length = %d\n", data, datalen);

        tds = cmd->con->tds_socket;

        dyn = tds_lookup_dynamic(tds, cmd->dyn_id);

        /* TODO */
        return CS_FAIL;
/*
        dyn = tds->dyns[elem];
        param = tds_add_input_param(dyn);
        param->column_type = _ct_get_server_type(datafmt->datatype);
        param->varaddr = data;
        if (datalen==CS_NULLTERM) {
                param->column_bindlen = 0;
        } else {
                param->column_bindlen = datalen;
        }
        param->is_null = indicator;

        return CS_SUCCEED;
*/
}


Note that the code which would actually do something is commented out
and the function unconditionally returns CS_FAIL.

So for the being, you cannot pass parameters to Cursor.execute() or
Cursor.callproc(), you must build a query string which does not use
parameters.

If I was really clever I would make Sybase.py adapt to the presense of
FreeTDS and turn have it shield you from that limitation in FreeTDS.

- Dave

-- 
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