Calculate distance in MySQL from Points

Distance.sql

DELIMITER $$
 
DROP FUNCTION IF EXISTS `test`.`distance` $$
CREATE FUNCTION `distance`(a POINT, b POINT) RETURNS double
DETERMINISTIC
COMMENT 'distance function'
BEGIN
RETURN round(glength(linestringfromwkb(linestring(asbinary(a), asbinary(b)))));
END $$
 
DELIMITER ;