Sort relative distance on the fly

Hi I am quite a newbie in Ruby. I want to sort a list of locations by
relative distance (shortest to farthest relative to my location) on the
fly. For example, let say I am at x and y coordinate, I have other
points in the map around me. I want to be able to list the other points
in terms of the shortest distance from me to the farthest. I store
longitude and latitude information on the database. However, I cannot
store the relative distance permanently, as (i) number of points change
in real time; and (ii) I don't have relationship with the other points,
which means the many-to-many tables are still empty.

Any ideas?

Google for "earth distance sql"... or trust that the below is right :slight_smile:

This assumes that some_table has columns for latitude and longitude and that you've set variables for latitude, longitude and radius (in miles) to search on.

SELECT * FROM some_table WHERE
(3960 * 2 * ASIN( SQRT( (1 - COS(RADIANS(latitude - #{latitude})))
/ 2 + COS(RADIANS(#{latitude}))
* COS(RADIANS(latitude))
* (1 - COS(RADIANS(longitude - #{longitude}))) / 2))) <= #{radius}

Philip Hallstrom wrote: