gistfile1.sql

CREATE PROCEDURE geodist (IN userid int, IN dist int) 
BEGIN

declare mylon double;
declare mylat double;
declare lon1 float;
declare lon2 float;
declare lat1 float;
declare lat2 float;

-- get the original lon and lat for the userid:
select longitude, latitude into mylon, mylat from users where id=userid limit 1;

-- calculate lon and lat for the rectangle (~69 miles per one degree):
set lon1 = mylon - dist / abs(cos(radians(mylat))*69);
set lon2 = mylon + dist / abs(cos(radians(mylat))*69);
set lat1 = mylat - (dist / 69);
set lat2 = mylat + (dist / 69);

-- run the query
select 
  destination.*,
  -- lots of Math here...just trust it - it works - I tested it...
  3956 * 2 * ASIN(SQRT(POWER(SIN((orig.lat-dest.lat)*pi()/180/2),2)+COS(orig.lat*pi()/180)*COS(dest.lat*pi()/180)*POWER(SIN((orig.lon-dest.lon)*pi()/180/2),2))) as distance
from
  users destination, users origin
where
  origin.id = userid
  and destination.longitude between lon1 and lon2
  and destination.latitude between lat1 and lat2
  having distance < dist
order by distance limit 10;

END