[GRASS-user] Tutorial & help needed::join tables (which are storedin postgres) and export result

[Sampson, David]

Hey Wqual,

I am starting to work with PGSQL/POSTGIS with GRASS and learning as I
go. Welcome to the club.

First I would encourage you to check out the estensive documentation
online... This might be what you need... Here are the docs on how to
join tables

http://www.postgresql.org/docs/8.1/static/tutorial-join.html

How to do it in grass?  Not sure, I'm learning the CLI to understand how
PG works. I'm no programer, I just learn the stuff I need to.

However, that said if GRASS can pass and exploit SQL commands then I am
sure this is possible. If it is not then getting some dicussion going on
the list is a great first step.

As for tutotirals, that's why I'm learning so I can create a hands on
tutorial... So perhaps we can get some people working together on this
using a common dataset.

Check out the http://grass.itc.it/community/sqlgrasslist.html for maybe
some more help. I have not ventured there yet so no idea if they can
help, but it makes sense.

Check out this SQL primer for grass 5.0
http://freegis.org/cgi-bin/viewcvs.cgi/~checkout~/grass/src.garden/grass
.postgresql/tutorial/index.html

As for front ends I have some experience with Pgadmin, but most books
from the library use the CLI so PGADMIN is on hold right now... But if
you are used to ORACLE/SDE combos it is verry similar, at least in the
way of layout and permissions.

Have not done becnh marking on file sizes and formats.


Hope some of this helps.

Cheers
 

-----Original Message-----
From: grassuser-bounces at grass.itc.it
[mailto:grassuser-bounces at grass.itc.it] On Behalf Of wqual
Sent: August 3, 2006 08:30
To: grassuser at grass.itc.it
Subject: [GRASS-user] Tutorial & help needed::join tables (which are
storedin postgres) and export result

Dear list,
I am still testing, what kind of database I should use for my work with
GRASS/QGIS. As my experiences with sqlite3 where not that positive
(large datasets took very much time to be read into sqlite), I started
working with postgres (and my first impression is that it's far more
faster). dbf is quick, but does not offer me the possibility to perform
"table-join", which I need every day. 
I am not that experienced with pg, therefore, I would like to ask you
folks some questions about "daily GIS work with postgres in GRASS":

* How can I join pg-tables in GRASS, can I export a joined theme to make
it permanent (for example, I would like to create a shapefile out of it
which contains all information of the join)

* Does anybody has experience with pg-frontends like knoda and pg_admin?

Working with tables on the command-line is hard for people who used
*other
programmes* before ;)

* what about large datasets: shapefiles with *qix-files seem to be
loaded faster compared the same theme in GRASS with its attributes in
postgres

* tutorials available for this pg-stuff inside of GRASS?

Any comments / hints are greatly appreciated!

Best regards,
Wolfgang 

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