MySQLfunction get distance between 2 points in km

func_get_distance.sql

use `your_schema`;
drop function if exists `get_distance`;

delimiter $$
use `your_schema`$$
create function `get_distance` (lat1 decimal(9,6), lng1 decimal(9,6), lat2 decimal(9,6), lng2 decimal(9,6)) returns decimal(10,3)
begin
  	declare R decimal(30,15);
	declare rlat1 decimal(30,15);
	declare rlat2 decimal(30,15);
	declare dLat decimal(30,15);
	declare dLng decimal(30,15);
  	declare distance decimal(30,15);
	declare a decimal(30,15);
	declare c decimal(30,15);

	set R = 6371; -- earth radisu in km
	set rlat1 = radians(lat1);
	set rlat2 = radians(lat2);

	set dLat = radians(lat2-lat1);
	set dLng = radians(lng2-lng1);

	set a = sin(dLat/2) * sin(dLat/2) + cos(rlat1) * cos(rlat2) * sin(dLng/2) * sin(dLng/2);
	set c = 2 * atan2(sqrt(a), sqrt(1-a));
	set distance = R * c;

  	return distance;
end$$

delimiter;