Union is trivial. Here's a query that generates a new set of polygons dissolved based on an attribute value:
create table newtable as select st_union(the_geom), attribute group by attribute; Overlay is non-trivial, and I leave that to someone else to provide good SQL. The simple case of finding all the overlapping parts is easy, but filling in the non-overlapping parts is harder. P On Mon, Sep 21, 2009 at 3:32 PM, Ravi <[email protected]> wrote: > Hi, > am using other FOSS GIS GRASS and OpenJUMP for > Polygon layers Union > and Intersection (overlay) > are there similar functions in postGIS THE LATEST RELEASE > > I have raised these issues some time before too. > http://postgis.refractions.net/pipermail/postgis-users/2008-May/019515.html > > Ravi Kumar > > > > Keep up with people you care about with Yahoo! India Mail. Learn how. > http://in.overview.mail.yahoo.com/connectmore > _______________________________________________ > 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
