GeoSearch Stored Procedure

gistfile1.sql

CREATE DEFINER=`root`@`localhost` PROCEDURE `get_nearby_clusters`(IN `mylat` FLOAT, IN `mylng` FLOAT, IN `dist` FLOAT)
	LANGUAGE SQL
	NOT DETERMINISTIC
	READS SQL DATA
	SQL SECURITY INVOKER
	COMMENT ''
BEGIN  
	declare lng1 float;  declare lng2 float; 
	declare lat1 float; declare lat2 float;
	
	-- Define a rectangle around the origin, delimiting the max range for possible clusters
	set lng1 = mylng-dist/abs(cos(radians(mylat))*69); 
	set lng2 = mylng+dist/abs(cos(radians(mylat))*69); 
	set lat1 = mylat-(dist/69);  
	set lat2 = mylat+(dist/69);

	-- Run the search query
	-- This will perform a Harvesine distance calculation between the origin and the tested point within the tolerable distance
	SELECT  
		d.*,  
		3956 * 2 * ASIN(SQRT(  POWER(SIN((mylat - d.lat) * pi()/180 / 2), 2) +  
		COS(mylat * pi()/180) *  COS(d.lat * pi()/180) *  POWER(SIN((mylng - d.lng) * pi()/180 / 2), 2)  )) 
			as distance
	FROM clusters d WHERE
		d.lng between lng1 and lng2 and
		d.lat between lat1 and lat2 
	HAVING distance < dist 
	ORDER BY distance 
	LIMIT 64;
	
END