// Praha, Drazdany

SET @lat1 = 50.0598058;
SET @lat2 = 51.0769658;
SET @lng1 = 14.3255396;
SET @lng2 = 13.6325016;

select
6371 * 2 * ASIN(SQRT(
            POWER(SIN((@lat1 - abs(@lat2)) * pi()/180 / 2),
            2) + COS(@lat1 * pi()/180 ) * COS(abs(@lat2) *
            pi()/180) * POWER(SIN((@lng1 - @lng2) *
            pi()/180 / 2), 2) ));