Mysql根据经纬度计算两者的距离

$res = db('rider')
                                ->where(['rider_id' => $info['rider_id']])
                                ->field('*, ( 6371 * acos( cos( radians(' . $info['latitude'] . ') ) * cos( radians( latitude ) ) * cos( radians( longitude ) - radians(' . $info['longitude'] . ') ) + sin( radians(' . $info['latitude'] . ') ) * sin( radians( latitude ) ) )) AS distance')
                                ->find();