PgAdmin can do it. The terminal can do it too, but i find pgAdmin more easy to work with.
Just go to the database you are working, open a query editor and try it. Dont forget about the considerations all the other made. The value returned will depend on your projection. george On Fri, Apr 3, 2009 at 1:48 PM, Aurora Geomatics <[email protected]>wrote: > Thank you George, > On 3-Apr-09, at 9:22 AM, George Silva wrote: > > Hello Aurora, > > In ArcGIS it's all different. In PostGIS you can use simple/complex SQL > queries to "calculate values" in a similar fashion of arcgis. > > The simplest of them all would be, in your case: > > ALTER TABLE table1 ADD COLUMN area_column double precision; > UPDATE table1 SET area_column = ST_AREA(the_geom); > > You can in that SQL query divide, multiply, and do whatever you want with > that result that will be written to the column area_column. > > > Pretty straight forward SQL statement. > Is this a matter of opening a Terminal session using psql monitor? > > Is it possible through pgAdmin or QGIS? > > Thanks. > > I hope that helps > > George > > On Fri, Apr 3, 2009 at 12:55 PM, Aurora Geomatics < > [email protected]> wrote: > >> Hello PostGIS users, >> >> I have just installed William Kyng's PostgeSQ/PostGIS packages for Mac OS >> X.5 >> >> I have been playing with pgAdmin and QGIS with importing shapefiles into >> PostGIS. Works dandy. >> >> Now I am wondering how to solve Attribute Calculations. >> >> Years of using ArcGIS and GRASS it is pretty straightforward on those >> apps, and am stumped with PostGIS Attribute calculations.. >> >> For example, using a polygon feature; >> >> Creating a new column, say AREA and filling with a calculation that is >> Hectares. >> >> Thanks! >> _______________________________________________ >> postgis-users mailing list >> [email protected] >> http://postgis.refractions.net/mailman/listinfo/postgis-users >> > > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > > > > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > >
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