FreeTDS Development Group

[Ken Seymour <kenaseymour AT yahoo.com>]

Brian,

This weekend, I decided to test the ODBC driver with
parameterized select statements.

To do this I used the pubs2 example database and did
the following:

select title from titles
where total_sales = ?

This requires calling, in order:

SQLPrepare
SQLBindParameter
SQLExecute

I debugged into SQLBindParameter and found that the
param_info structure was not allocated.  So I added
a call to tds_alloc_param_result (in tds/mem.c).
This caused a SEGV and upon further inspection,
this routine looks like it is missing a malloc.

It was after I added this and got SQLBindParameter 
working that I discovered that SQLExecute does not
make use of the parameters and Sybase attempts to 
give me a message of 'syntax error near ?' or 
something like that.

To my knowledge, there are not parameter routines in
tds (or dblib for that matter).  So I suppose I will
have to implement it on the client side.
Since I suspect that SQLPrepare can be called once
and SQLExecute several times with different parameter
values (in the same bound variables), I will need
to keep the original SQL text, substitute the question
marks for the stored parameter values, and pass along
the translated SQL text to TDS.

I am getting ready to check in changes to odbc/odbc.c
and tds/mem.c.  I wanted to check in with you first
since this is outside the odbc tree.

I will add

   param_info->columns[0] = (TDSCOLINFO*)
      malloc (sizeof (TDSCOLINFO));

before the second memset in if (!oldparam) and add

                  
param_info->columns[param_info->num_cols-1] =         
   (TDSCOLINFO*) malloc (sizeof (TDSCOLINFO));

before the second memset in the else block.

What do you think?

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