[libdbi-devel] Re: [libdbi-users] stupid question about nulls

[<m.e...@ls...>]

Thanks Christian! I didn't even think of looking at the length...

I only have pqsql, but it looks as if for this one at least the length
is always 0 except for strings, where it is equal to the length of the
string (as you say it does not seem to implement what's in the comment).

I tried implementing your suggestion myself in dbd_pgsql.c, and got as
far as

512a513
>                       row->field_sizes[curfield] = -1;

Unfortunately, now I get a length of -2 for NULLs???

Maybe someone familiar with the driver could have a look at this? It
would be neat to be able to distinguish between NULL, "" and 0...

Max



On Thu, 2004-07-29 at 12:41, Christian Stamgren wrote:
> Hello.
> 
> I belive this is a short comming of the libdbi-drivers as it looks today. 
> 
> By reading dbi-dev.h you will find this row part of dbi_row_t struct.:
> 
> unsigned long long *field_sizes; /* NULL field = 0, string field = len, 
> anything else = -1 */
> 
> But the drivers does not implemet it this way. 
> 
> 
> I'll suggest that we change it so that:
> NULL field = -1, string field = len, anything else = 0
> 
> That way we will have distinction between NULL and a string of 0 chars (which 
> is not the same as NULL).
> 
> It would then be easy to implement a couple of funtions like: 
> 
> dbi_result_field_isnull(result, "fieldname");
> or 
> dbi_result_field_isnull_idx(result, 2);
> 
> 
> 
> Regards, 
> 
> //Christian
> 
> 
> 
> On Wednesday 28 July 2004 15.45, m.e...@ls... wrote:
> > Hi,
> >
> > I have been running some queries that return NULLs at times (in fields
> > that contain doubles).
> >
> > It looks as if you use dbi_result_get_double() you get 0 whenever the
> > query returned a NULL.
> >
> > How can I distinguish between a NULL and 0? It looks like I might have
> > missed something obvious here...
> >
> > Thanks,
> >
> > Max
> >
> >
> > -------------------------------------------------------
> > This SF.Net email is sponsored by BEA Weblogic Workshop
> > FREE Java Enterprise J2EE developer tools!
> > Get your free copy of BEA WebLogic Workshop 8.1 today.
> > http://ads.osdn.com/?ad_id=4721&alloc_id=10040&op=click
> > _______________________________________________
> > libdbi-users mailing list
> > lib...@li...
> > https://lists.sourceforge.net/lists/listinfo/libdbi-users
>