地图按范围查找-经纬度计算

private const double EARTH_RADIUS = 6378.137;//地球半径
        private static double rad(double d)
        {
            return d * Math.PI / 180.0;
        }

        public static double GetDistance(double lat1, double lng1, double lat2, double lng2)
        {
            double radLat1 = rad(lat1);
            double radLat2 = rad(lat2);
            double a = radLat1 - radLat2;
            double b = rad(lng1) - rad(lng2);

            double s = 2 * Math.Asin(Math.Sqrt(Math.Pow(Math.Sin(a / 2), 2) +
             Math.Cos(radLat1) * Math.Cos(radLat2) * Math.Pow(Math.Sin(b / 2), 2)));
            s = s * EARTH_RADIUS;
            s = Math.Round(s * 10000) / 10000;
            return s;
        }

select id,hotel_code,bname,image,serviceId,fjmoney,score,lon,lat,(2 * 6378.137* ASIN(SQRT(power(SIN(PI()*(28.984223-lat)/360),2)
+COS(PI()*28.984223/180)* COS(lat * PI()/180)*power(SIN(PI()*(112.92671-lon)/360),2)))) as distance 
 into #temp from hotelid