[postgis-users] how to select points outside polygons?

[Vishal Mehta]

I have a point layer and a polygon layer. How do I select points that are NOT contained within polygons?

For example, this query correctly selects points contained by polygons
--
                select powerplants.gid, plantname
                from powerplants, pca_huc
                where state = 'CA'
                AND
                st_contains(pca_huc.geom,powerplants.geom)
                order by powerplants.gid;
--

I tried to get the inverse selection using st_disjoint instead of st_contains , but that did not work. I also tried using NOT and EXCEPT without success (although I may not have constructed the latter queries correctly..)

Thanks!
Vishal




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