[GRASSLIST:10145] Re: v.to.db option=query: issue with 2 layers and multiple categories

[Radim Blazek]

On 2/3/06, Maciek Sieczka <werchowyna at epf.pl> wrote:
> On Thu, 2 Feb 2006 09:41:10 +0100
> Radim Blazek <radim.blazek at gmail.com> wrote:
>
> Radim,
>
> > Hi,
> > I am satisfied to read that people are using and understand these
> > more complex features in GRASS vector model.
> >
> > I think (I hope) that the problem is that you have more cats
> > (1,2) in the layer 1 on the point.
>
> > If you use qcolumn=height v.to.db queries the database for this point
> > with select height from testing_pt_nodupl2_1 where cat=1 or cat=2
> > The result is 2 rows (100.5 twice). It is impossible to upload
> > 2 values into one row in layer 2. If you have more cats in queried
> > layer on the same geometry it is necessary to use an aggregate
> > function, for example qcolumn=avg(height).
> >
> > Does it work?
>
>
>
> Right! There are indeed two categories in layer 1, for the same
> geometry element. Now that you made me notice it it's obvious wy the
> error, thanks.
>
> However, there are _also_ two categories for the same geometry in layer
> 2 (10,11). I mean - I understand I couldn't upload 2 values into one
> "row". But since in this particular case in both layer 1 and 2 there
> are two "rows", isn't it somehow different? Just wondering.

If it is not uploaded to both rows  in layer 2 (10,11) then it is a bug.

Radim

> Best,
> Maciek
>
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