You can use the spacial functions and spacial type columns http://dev.mysql.com/doc/refman/5.5/en/spatial-extensions.html
Here it's a great example to use spacial functions! http://www.mysqlperformanceblog.com/2013/10/21/using-the-new-spatial-functions-in-mysql-5-6-for-geo-enabled-applications/
Or you can define a custom function
CREATE DEFINER=`test`@`%` FUNCTION `geoDistance`(`lon1` DOUBLE, `lat1` DOUBLE, `lon2` DOUBLE, `lat2` DOUBLE)
RETURNS double
LANGUAGE SQL
DETERMINISTIC
NO SQL
SQL SECURITY DEFINER
COMMENT ''
BEGIN
DECLARE v DOUBLE;
SELECT cos(radians(lat1))
* cos(radians(lat2))
* cos(radians(lon2) - radians(lon1))
+ sin(radians(lat1))
* sin(radians(lat2)) INTO v;
RETURN IF(v > 1, 0, 6371000 * acos(v));
END
then call
SELECT geoDistance(X(point1), Y(point1), X(spoint2), Y(point2))
result comes in meters