php做附近的人，根据距离由近到远进行排序

<code><?php
//以当前用户经纬度为中心,查询5000米内的其他用户
$y = 5000 / 110852; //纬度的范围
$x = 5000 / (111320*cos($lat)); //经度的范围
$sql = '
select * from user where 
    lat > ($lat-$y) and lat < ($lat+$y) and 
    lon > ($lon-$x) and lon < ($lon+$x);
';</code>

<code><?php
function distance($lat1, $lon1, $lat2, $lon2) {
    $R = 6371393; //地球平均半径,单位米
    $dlat = deg2rad($lat2-$lat1);
    $dlon = deg2rad($lon2-$lon1);
    $a = pow(sin($dlat/2), 2) + cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * pow(sin($dlon/2), 2);
    $c = 2 * atan2(sqrt($a), sqrt(1-$a));
    $d = $R * $c;
    return round($d);
}
echo distance(0, 0, -1, 0); // 111202米</code>

<code>"filtered": {
    "query" : {
        "match_all" : {}
    },
    "filter": {
      "geo_distance": {
        "distance": 20,
        "distance_unit": "km",
        "location": {
          "lat" : 40.11116,
          "lon" : -71.34115
        }
      }
    }
}</code>