Question

我目前有一个MySQL表，其结构如下：

id         name     lon            lat  
-----      -----    -----------    -----------
1          Mark     -76.316528     40.036027
2          John     -95.995102     41.25716
3          Paul     -82.337036     29.645095
4          Dave     -82.337036     29.645095
5          Chris    -76.316528     40.036027

我当前查询数据库以查看用户位置是否在给定位置的某个英里范围内的方式就是这样做。

function Haversine($lat_from, $lon_from, $lat_to, $lon_to) {
    $radius = 6371000;
    $delta_lat = deg2rad($lat_to-$lat_from);
    $delta_lon = deg2rad($lon_to-$lon_from);

    $a = sin($delta_lat/2) * sin($delta_lat/2) +
        cos(deg2rad($lat_from)) * cos(deg2rad($lat_to)) *
        sin($delta_lon/2) * sin($delta_lon/2);
    $c = 2*atan2(sqrt($a), sqrt(1-$a));

    // Convert the distance from meters to miles
    return ceil(($radius*$c)*0.000621371);
}

// Set the given location to NYC
$my_lon = -73.9844;
$my_lat = 40.7590;

// Query the DB for all of the users
$sql = "SELECT * FROM users";
$result = mysqli_query($con, $sql)or die(mysqli_error($con));
$count = mysqli_num_rows($result);
$i = 0;

while($row = mysqli_fetch_assoc($result)) {
    $lon[$i] = $row['lon'];
    $lat[$i] = $row['lat'];

    $i++;
}

for($i=0;$i<$count;$i++) {
    // Calculate the distance between each user's location and my location
    $distance = Haversine($my_lat, $my_lon, $lat[$i], $lon[$i);

    if($distance < 50) {
        echo "Close enough";
    }
}

这适用于表中只有几百行。但是，现在我有成千上万行，检查这么多行已被证明是非常耗时的。我想知道是否有办法使用Haversine公式来查询半径50英里范围内的行。

Answer 1

余弦公式的球面定律
（37和-122是你的半径中心的纬度和经度）

SELECT id, ( 3959 * acos( cos( radians(37) ) * cos( radians( lat ) ) 
    * cos( radians( long ) - radians(-122) ) + sin( radians(37) ) * sin(radians(lat)) ) ) AS distance 
FROM myTable
HAVING distance < 50
ORDER BY distance

功能

最快
与Harvesine Formula相似的精度

Haversine Formula

SELECT id, 3956 * 2 * ASIN(SQRT(POWER(SIN((37 - abs(lat)) * pi()/180 / 2), 2)
       + COS(37 * pi()/180 ) * COS(abs(lat) * pi()/180)
       * POWER(SIN((-122 – long) * pi()/180 / 2), 2) )) as  distance
FROM myTable
HAVING distance < 50
ORDER BY distance

功能

快速
对浮点错误更强大

请注意， 3959是以英里为单位的地球半径。地球半径（km）：6371

您可以找到更多信息here

查询MySQL在给定英里半径范围内的纬度和经度坐标

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