I have somewhat of a newbie question:
How can I relate entries in the polygon table with entries in the points table in a reliable way?
A concrete example: getting all major german cities and their polygons. My naive approach:
This query works great for getting all 83 major cities:
SELECT name FROM planet_osm_point WHERE place = 'city'
When using the result in a polygon query though…
SELECT name FROM planet_osm_polygon WHERE boundary='administrative' AND name in (SELECT name FROM planet_osm_point WHERE place = 'city') ;
… the result contains many duplicates:
Berlin Potsdam Magdeburg Magdeburg Magdeburg ...
I realize, that there are different admin_level’s which I would have to restrict as well.
I am looking for insights into how I can connect planet_osm_polygon and planet_osm_point more systematically.
Maybe using osm_ids or something similar.
Thank you for reading