Setting Unit in POSTGIS

Question

I'm new to PostGIS so my question might sound silly. Currently working with Points to represent geographical locations (with latitude and longitude only) and was wondering how I can use [ST_DWithin][3] with meters as a unit.

I can't find the right way and been lost in documentation trying to solve this issue.

Answer 1

You need to make sure that your points are geography rather than geometry, as explained in the manual.

So you want a query like:

SELECT s.gid, s.school_name
    FROM schools s
        LEFT JOIN hospitals h ON ST_DWithin(s.geom::geography, h.geom::geography, 3000)
    WHERE h.gid IS NULL;