Distance comparison of geolocations with a location given.

geolocation_distance.sql

SET @c1 = PI()/180,
	@c2 = PI()/360,
	@r = 6378137,
	@lat1 = ?,
	@lng1 = ?;
SELECT latitude, longitude, distance
FROM (
	SELECT	*,
		@lat2 := latitude,
		@lng2 := longitude,
		@dlat := @lat2 - @lat1,
		@dlng := @lng2 - @lng1,
		@a := (SIN(@dlat * @c2) * SIN(@dlat * @c2)
				+ COS(@lat1 * @c1) * COS(@lat2 * @c1) * SIN(@dlng * @c2) * SIN(@dlng * @c2)),
		@c := 2 * ATAN2(sqrt(@a), SQRT(1 - @a)),
		@d := @r * @c as distance
	FROM `locations`
) as x
WHERE distance <= ?;