Question

I would like to compare and get only stations which are within a distance range ONE TO THE OTHER. Let say I have 3 stations A-B-C they all have a position x-y-z. I would like to get the stations that are distant from 30 meters (I have a function to compute the distance so let’s call it distance(x,y)).

SELECT * FROM Station WHERE distance(Station1, Station2) < 30

My problem is how can you compare distance of two different rows Station1 and Station2?

Thanks!!!

Answer 1

You could do something like this:

select a.*
from station a
inner join station b
on distance(a.station_id, b.station_id) < 30;