[GRASS-user] Learning to use vector layers

[Daniel Victoria]

Hi Jaime,

No, all data, for all stations and all months/days are in one big
table! I guess I'll just keep changing the network connection for now.

Cheers
Daniel

On 3/26/07, Jaime Carrera <jaicarrerahdez at yahoo.com> wrote:
>
> Hi Daniel,
>
> Well, it depends on your database structure. If you have one table for each
> month:
>
> SELECT t1.id, t1.east, t1.north, t1.rain,t2.rain,t3.rain FROM table1 as t1,
> table2 as t2, table3 as t3 WHERE...
>
> Jaime
>
> ----- Mensaje original ----
> De: Daniel Victoria <daniel.victoria at gmail.com>
> Para: Jaime Carrera <jaicarrerahdez at yahoo.com>
> CC: grass <grassuser at grass.itc.it>
> Enviado: lunes, 26 de marzo, 2007 16:36:23
> Asunto: Re: [GRASS-user] Learning to use vector layers
>
>
> Yea, that could do it also, just have to figure out how to perform
> different queries for each column so I'd have average January on  col
> 1 and avg February on two and so on. Probably a bunch of table
> updates?
>
> Thanks
> Daniel
>
> On 3/26/07, Jaime Carrera <jaicarrerahdez at yahoo.com> wrote:
> > Hi Daniel,
> >
> > You could also generate a table like this:
> >
> > id|easting|northing|9001|9002|9003|...|9012|9101|...
> >
> > Then you have your data in one table which can be
> > linked to the vector file. Such a table can be
> > generated from other tables using SQL commands.
> >
> > HTH
> >
> > Jaime
> >
> >
> > --- Daniel Victoria <daniel.victoria at gmail.com>
> > escribió:
> >
> > > Hi all,
> > >
> > > I have a vector problem and I think it might be a
> > > job for vector layers.
> > > I have a postgresql table with daily meteorological
> > > station data (~10
> > > years, 300 stations) and I'd like to get average
> > > monthly precipitation
> > > for each station.
> > > That I can easily do with a SQL query, generating a
> > > view and attaching
> > > the view to a vector file where the CAT column is
> > > the station number.
> > > The problem is, I can only attach one SQL view at a
> > > time since the
> > > vector file has only one category (from what I read,
> > > it's one category
> > > per layer connection correct?)
> > >
> > > So, I though about some options:
> > > 1) either generate 1 vector file for each month -
> > > simple but then I
> > > don't learn about layers
> > > 2) keep changing the database connection for each
> > > month - works but
> > > seems kind of improvisation
> > > 3) Use layers, one layer for each month. I'd have
> > > the advantage of not
> > > having categories for stations with no data for a
> > > specific month for
> > > example and also, I'd learn about layers
> > >
> > > So, the proper questions:
> > > Does this sounds like a job for vector layers?
> > > How do I add categories to a vector file but, the
> > > categories should
> > > come from a column in a SQL view? From what I read,
> > > v.category can
> > > only add sequential cats and I'd like the cats to be
> > > the station
> > > number.
> > >
> > > Cheers and sorry for the long email
> > > Daniel
> > >
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> > >
> >
> >
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>
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