数据库根据经纬度查询数据并根据距离排序：

SELECT *,
    ROUND(
        6378.138*2*ASIN(
            SQRT(
                POW(
                    SIN(
                        (纬度*PI()/180-latitude*PI()/180)/2
                    ),2
                )+COS(纬度*PI()/180)*COS(latitude*PI()/180)*POW(
                    SIN(
                        (经度*PI()/180-longitude*PI()/180)/2
                    ),2
                )
            )
        )*1000
    ) AS lang   
FROM `circle_community` ORDER BY lang ASC"

PHP根据两点的经纬度计算距离

function radian($d) {
    return $d * 3.1415926535898 / 180.0;
}


function distanceCalculate($longitude1, $latitude1, $longitude2, $latitude2) {
    $radLat1 = radian ( $latitude1 );
    $radLat2 = radian ( $latitude2 );
    $a = radian ( $latitude1 ) - radian ( $latitude2 );
    $b = radian ( $longitude1 ) - radian ( $longitude2 );


    $s = 2 * asin ( sqrt ( pow ( sin ( $a / 2 ), 2 ) + cos ( $radLat1 ) *
            cos ( $radLat2 ) * pow ( sin ( $b / 2 ), 2 ) ) );
    $s = $s * 6378.137; //乘上地球半径，单位为公里
    $s = round ( $s * 10000 ) / 10000; //单位为公里(km)
    return $s; //单位为km
}