PHP - 以while（）循环的升序输出结果

Question

我需要根据循环内的计算显示结果。循环的结果应该是 $distance 的升序。

    $sql = "SELECT DISTINCT * FROM cinemas WHERE city='$city'";

    $result = $conn->query($sql);

    if ($result->num_rows > 0) {

        while($row = $result->fetch_assoc()) {



    $lat1 = $_GET['lat'];
    $lon1= $_GET['lon'];
    $lat2 = $row['latitude'];
    $lon2 = $row['longitude'];

    //starting calculating the distance

      $theta = $lon1 - $lon2;
      $dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) +  cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta));
      $dist = acos($dist);
      $dist = rad2deg($dist);
      $miles = $dist * 60 * 1.1515;
      $unit = $miles * 1.609344;

    $distance = substr($unit,0,4);
echo $row['cinemaname'].$distance;

}}

如何根据 $distance 升序显示结果？

显示为：

cinema name 20 km
cinema name 5 km
cinema name 30 km
cinema name 3 km

我需要在：

cinema name 3 km
cinema name 5 km
cinema name 20 km
cinema name 30 km

Answer 1

将 while 中的返回值保存在这样的数组中：

$cinema[$i]['cinemaname'] = $row['cinemaname'];
$cinema[$i]['distance'] = $distance;

并在此之后制作：

function sortByOrder($a, $b) {
    return $a['distance'] - $b['distance'];
}

usort($cinema, 'sortByOrder');

现在你有你的订单:)

这是你的代码：

$sql = "SELECT DISTINCT * FROM cinemas WHERE city='$city'";

$result = $conn->query($sql);
$cinema = array();
$i = 0;
if ($result->num_rows > 0) {

    while($row = $result->fetch_assoc()) {
       $lat1 = $_GET['lat'];
       $lon1= $_GET['lon'];
       $lat2 = $row['latitude'];
       $lon2 = $row['longitude'];

       //starting calculating the distance

       $theta = $lon1 - $lon2;
       $dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) +  cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta));
       $dist = acos($dist);
       $dist = rad2deg($dist);
       $miles = $dist * 60 * 1.1515;
       $unit = $miles * 1.609344;

       $distance = substr($unit,0,4);
       $cinema[$i]['cinemaname'] = $row['cinemaname'];
       $cinema[$i]['distance'] = $distance;
       $i++;
    }
}

function sortByOrder($a, $b) {
   return $a['distance'] - $b['distance'];
}

usort($cinema, 'sortByOrder');

Answer 2

    $sql = "SELECT DISTINCT * FROM cinemas WHERE city='$city'";



       $result = $conn->query($sql);
    $distanceArray=array('');
$i=0;
        if ($result->num_rows > 0) {

        while($row = $result->fetch_assoc()) {



    $lat1 = $_GET['lat'];
    $lon1= $_GET['lon'];
    $lat2 = $row['latitude'];
    $lon2 = $row['longitude'];

    //starting calculating the distance

      $theta = $lon1 - $lon2;
      $dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) +  cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta));
      $dist = acos($dist);
      $dist = rad2deg($dist);
      $miles = $dist * 60 * 1.1515;
      $unit = $miles * 1.609344;

    $distance = substr($unit,0,4);
    $distanceArray[$i]=$row['cinemaname'].$distance;
$i++;
}}
sort($distanceArray);
foreach($distanceArray as $nameDistance)
{
echo $nameDistance; echo '<br>';
}

Answer 3

您也可以编写一个 MySQL 函数来计算距离，然后按升序查询。 像这样：

$sql = "SELECT DISTINCT *, distance($lat1,$lon1) AS dist  FROM cinemas WHERE city='$city' ORDER BY dist ASC";

当然要事先写好对应的MySQL函数。