I have a point shapefile called pointA that has a field called fieldB, and a polygon file called polygonC, and I want to calculate the sum of fieldB for all the points that are within polygonC
How to do this?
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1 Answer
Load your shapefile(s) in as per instructions from http://suite.opengeo.org/docs/latest/dataadmin/pgGettingStarted/shp2pgsql.html
Then query using something like
SELECT sum(pointA.fieldB) FROM pointA, polygonC WHERE ST_Within(pointA.the_geom, polygonC.the_geom) AND polygonC.id = ? 
- 1I think he intends to get all the points within the polygons, the last line ( second condition in where ) is optional, if I understood well what he wantsHicham Zouarhi– Hicham Zouarhi2016-07-15 16:03:31 +00:00Commented Jul 15, 2016 at 16:03
- Hey @HichamZouarhi! Well I'm getting an error saying PolygonC does not exist when the table is clearly there. ERROR: relation "polygonC" does not existLuffydude– Luffydude2016-07-15 16:17:10 +00:00Commented Jul 15, 2016 at 16:17
- 1Hi there @Luffydude, one of the problems with postgresql is the name of tables with caps, that's why you'll have to change it to "polygonC"Hicham Zouarhi– Hicham Zouarhi2016-07-15 16:24:06 +00:00Commented Jul 15, 2016 at 16:24
- The query worked now but nothing happened, the result box is completely emptyLuffydude– Luffydude2016-07-15 16:26:40 +00:00Commented Jul 15, 2016 at 16:26
- 1I tried it in my configuration and it worked, have you tried it without the last condition ( AND polygonC.id = ? ) ?Hicham Zouarhi– Hicham Zouarhi2016-07-15 16:40:42 +00:00Commented Jul 15, 2016 at 16:40