Sunday, October 12, 2014

Example SpatiaLite query to find neighbors of a polygon

A common spatial query is to find all the neighbor polygons touching a subject polygon. The screenshot below shows a SpatiaLite database of selected country feature polygons.

If you want to find all the neighboring countries of the country Canada, the following SpatiaLite SQL query can be used.
select b.name
from country a, country b
where touches(a.geometry, b.geometry)
and a.name = 'Canada'


The result 'USA' is returned.
 

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