如果您在数据库中存储了纬度和经度,并且需要计算两个坐标之间的距离。您可以使用MySQL函数如何计算它?
如果您在数据库中存储了纬度和经度,并且需要计算两个坐标之间的距离。您可以使用MySQL函数如何计算它?
在搜索了一段时间后,我放弃了并自己编写了代码。我能够将一些其他的代码适应为以下的MySQL函数。
DELIMITER $$
/*
Takes two latitudes and longitudes in degrees. You could comment out the conversion if you want to pass as radians.
Calculate the distance in miles, change the radius to the earth's radius in km to get km.
*/
DROP FUNCTION IF EXISTS GETDISTANCE$$
CREATE FUNCTION GETDISTANCE
(deg_lat1 FLOAT, deg_lng1 FLOAT, deg_lat2 FLOAT, deg_lng2 FLOAT)
RETURNS FLOAT
DETERMINISTIC
BEGIN
DECLARE distance FLOAT;
DECLARE delta_lat FLOAT;
DECLARE delta_lng FLOAT;
DECLARE lat1 FLOAT;
DECLARE lat2 FLOAT;
DECLARE a FLOAT;
SET distance = 0;
/*Convert degrees to radians and get the variables I need.*/
SET delta_lat = radians(deg_lat2 - deg_lat1);
SET delta_lng = radians(deg_lng2 - deg_lng1);
SET lat1 = radians(deg_lat1);
SET lat2 = radians(deg_lat2);
/*Formula found here: http://www.movable-type.co.uk/scripts/latlong.html*/
SET a = sin(delta_lat/2.0) * sin(delta_lat/2.0) + sin(delta_lng/2.0) * sin(delta_lng/2.0) * cos(lat1) * cos(lat2);
SET distance = 3956.6 * 2 * atan2(sqrt(a), sqrt(1-a));
RETURN distance;
END$$
DELIMITER ;