DELIMITER $$   
  
DROP FUNCTION IF EXISTS `GetDistance`$$   
  
CREATE FUNCTION `GetDistance`(   
 lat1 numeric(9,6),   
 lon1 numeric(9,6),   
 lat2 numeric(9,6),   
 lon2 numeric(9,6)   
) RETURNS decimal(10,5)   
BEGIN  
 DECLARE x decimal(20,10);   
 DECLARE pi decimal(21,20);   
 SET pi = 3.14159265358979323846;   
 SET x = sin( lat1 * pi/180 ) * sin( lat2 * pi/180  ) + cos(   
 lat1 *pi/180 ) * cos( lat2 * pi/180 ) * cos( abs( (lon2 * pi/180) -   
 (lon1 *pi/180) ) );   
 SET x = atan( ( sqrt( 1- power( x, 2 ) ) ) / x );   
 RETURN ( 1.852 * 60.0 * ((x/pi)*180) ) / 1.609344;   
END$$   
  
DELIMITER ;