[GRASS5] Re: [GRASSLIST:10145] Re: v.to.db option=query: issue with 2 layers and multiple categories

[Radim Blazek]

But you are doing still the same error. You have to use
qcolumn=avg(elevation)

Radim

On 2/5/06, Maciek Sieczka <werchowyna at epf.pl> wrote:
> Radim,
>
> On Fri, 3 Feb 2006 19:17:42 +0100
> Radim Blazek <radim.blazek at gmail.com> wrote:
>
> > 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:
> > >
> > > > 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?
> > >
> > > 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.
>
> It isn't uploaded indeed. I doublechecked on another simple example
> just to make sure. The situation was as follows:
>
> - there are categories 1,2 in layer 1; the attribute name is
> "elevation"; for category 1 elevation=100, for cat 2 elevation=200.
>
> - there are categories 10,11 in layer2; the attribute name is
> "elevation2"
>
> - trying to populate "elevation2" in layer 2 (cat 10,11) with
> "elevation" from layer 1 (cat 1,2) results in an error - the
> "elevation2" for cat 10,11 is set to NULL:
>
> v.to.db map=nowy_pt_nodup type=point layer=2 qlayer=1 option=query
> column=elevation2 qcolumn=elevation Reading data trom the map ...  100%
> Querying database ... WARNING: Multiple query results, output value set
> to NULL (category 3) 100%
> WARNING: Multiple query results, output value set to NULL (category 2)
> Updating database ...  100%
> 4 categories read from map
> 4 records selected from table
> 4 categories read from map exist in selection from table
> 0 categories read from map don't exist in selection from table
> 4 records updated/inserted
> 0 update/insert errors
>
> So this is a bug? Fixable?
>
> Maciek
>
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