Aurora Geomatics 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.
alter table mytable add column area float;
update mytable set area=st_area2d(the_geom)*factor2convert2hectares;
There are some potential issues related to what projection you are in,
but I will let others expound on those.
-Steve
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