Hi Surya, you can try something like that: SELECT ws.name,dt.name, sum(ST_area(ST_intersection(ws.the_geom,dt.the_geom))) FROM watersheds as ws, districts as dt WHERE ST_intersects(ws.the_geom,dt.the_geom) GROUP BY ws.name,dt.name ORDER BY dt.name
Fred. On Sun, Sep 21, 2008 at 3:37 AM, surya <[EMAIL PROTECTED]> wrote: > Dear List, > > I have two tables, one table contains 5 polygons depicting 5 watersheds > or river basin boundaries. Another table contain district bondaries. Using > ST-contain function below, I have obtained districts belong to a certain > watershed . My qestion is how to calculate area of each district contained > in a certain watershed using sum(area)(), taking into consideration that one > district might be splitted in two or more different watershed > > SELECT watersheds.name, districts.name > FROM watersheds, districts > WHERE ST_contains (watersheds.the_geom, districts.the_geom) > GROUP BY watersheds.name, districts.name ; > > best regards, > > surya > > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users >
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