Hi, It looks like you're having a little bit of trouble with the SQL. That is understandable though, your problem is a little tricky, because it requires you to nest a query.
You should first note that it is not possible to have two FROM statements in a single query. Start by breaking down the problem into individual parts: 1) You need to collect both geometry columns each into a single collection. You can do this with two separate queries: select st_collect(pkt) as first_set from pktbsp1; select st_collect(pkt) as second_set from pktbsp2; 2) Now, you need to find a way to have the result of both these tables in a single place. This is done by nesting the two above queries into another query. select x.first_set, y.second_set from (select st_collect(pkt) as first_set from pktbsp1) x, -- I could have used JOIN instead of a comma. (select st_collect(pkt) as second_set from pktbsp2) y; If you're having trouble figuring out how the query nesting works, I suggest brushing up your SQL at sqlzoo.net. 3) Now, you can compare these two geometries. So the full query is: select x.first_set && y.second_set from -- Note that st_intersects (x.first_set,y.second_set) would be fine too (select st_collect(pkt) as first_set from pktbsp1) x, (select st_collect(pkt) as second_set from pktbsp2) y; That will return a single row with a single column: t or f. Hope that helps, aman -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Jan Saalbach Sent: August 20, 2010 10:02 AM To: PostGis Users List Subject: [postgis-users] using && operator Hi List, how do I check if two 3d-point sets overlap? I see the && operator should be able to compare the bounding boxes, but how do I do it? I can not get the && or ST_Intersects function to work. Here is what I am trying to do: SELECT ST_Collect(pkt) FROM pktbsp && ST_Collect(pkt) FROM pktbsp2; pkt are GeometryColumns filled with 3dpoints. pktbsp and pktbsp2 are the respective tables. How can I check this? Reagrds, Jan _______________________________________________ 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
