MySQL计算坐标点之间距离

#计算两坐标点之间距离，单位米

-- 经度相同,维度不同,结果大致相等
select st_distance_sphere(point(122.45,31.13), point(122.45, 31.93)) as distance;
select st_distance(point(122.45,31.13), point(122.45, 31.93)) * 111195 as distance;

-- 经度不同,维度相同,结果差异较大
select st_distance_sphere(point(121.45,31.13), point(129.45, 31.13)) as distance;
select st_distance(point(121.45,31.13), point(129.45, 31.13)) * 111195 as distance;

-- 经度维度都不同,结果差异较大
select st_distance_sphere(point(121.45,31.13), point(129.45, 39.13)) as distance;
select st_distance(point(121.45,31.13), point(129.45, 39.13)) * 111195 as distance;

//java代码计算两坐标点之间距离

   org.gavaghan
   geodesy
   1.1.3



public static Double calcGeodeticCurve(Double fromLatitude, Double fromLongitude, Double toLatitude, Double toLongitude) {
        GlobalCoordinates source = new GlobalCoordinates(fromLatitude, fromLongitude);
        GlobalCoordinates target = new GlobalCoordinates(toLatitude, toLongitude);
        //对比百度地图，计算结果和Sphere坐标系计算结果一致，表明计算结果正确，WGS84坐标系的计算结果存在几十米的误差。
        GeodeticCurve geoCurve = new GeodeticCalculator().calculateGeodeticCurve(Ellipsoid.Sphere, source, target);
        return geoCurve.getEllipsoidalDistance();
}

@Test
public void test2(){
        Double distance = Utils.calcGeodeticCurve(31.13, 121.45, 39.13, 129.45);
        System.out.println("距离:" + distance + "米");
}

//距离:1148121.7604524833米

有种说法：st_distance 计算的结果单位是度，需要乘111195（地球半径: 6371000*PI/180）将值转化为米才是坐标点之间距离。这种说法不够准确，每个坐标点所在维度不同，每度所代表的长度也是不同的，只有在经度相同维度不同时结果才是大致准确的。

mysql 5.7之后又有了一个st_distance_sphere(point(x,y),point(x,y))函数来计算坐标点距离，这个就比较准确一些。

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