php - 仅从数据库中获取最后 10 个数据，但以相反的方式打印数组

Question

我正在使用图表，我需要从我的数据库中获取最后 10 个数据并将其打印到我的图表中。好吧，我可以很容易地做到这一点，但问题是，数据正在以相反的方式打印，所以不是像这样打印，这只是示例:1 2 3 4 5，它正在打印 5 4 3 2 1 . 我需要它以正常方式打印。
这是我的代码:

  $id = $_SESSION['userId']; 
  $dBname = "infosensor";
  $conn = mysqli_connect($servername, $dBUsername, $dBPassword, $dBname);

  $sql = "SELECT sensor1, sensor2, sensor3, dias FROM `$id` ORDER BY id DESC LIMIT 10;";

  $result = mysqli_query($conn, $sql);
  $jsonsensor1 = array();
  $jsonsensor2 = array();
  $jsonsensor3 = array();
  $jsonsensorsum = array();
  $date = array();
  if (mysqli_num_rows($result) > 0)
  {
    while ($row = mysqli_fetch_assoc($result))
    {
      $jsonsensor1[] = intval($row['sensor1'] * ($p = pow(10, 2))) / $p;
      $jsonsensor2[] = intval($row['sensor2'] * ($p = pow(10, 2))) / $p;
      $jsonsensor3[] = intval($row['sensor3'] * ($p = pow(10, 2))) / $p;
      $jsonsensorsum[] = intval(($row['sensor1'] + $row['sensor2'] + $row['sensor3']) * ($p = pow(10, 2))) / $p;

      //Data
      $geral = (date('d/m/y', strtotime(str_replace('.', '-', $row['dias']))));
      $date[] = $geral;

      //Horario
      $horario = (date('H:i:s', strtotime(str_replace('.', '-', $row['dias']))));    
      $tempo[] = explode(',', $horario);
    } 
  }

  $data = [$jsonsensor1,$jsonsensor2,$jsonsensor3,$jsonsensorsum, $date];

  echo json_encode($data);

问题出在这里:

$sql = "SELECT sensor1, sensor2, sensor3, dias FROM `$id` ORDER BY id DESC LIMIT 10;";

Answer 1

怎么样:

SELECT sensor1, sensor2, sensor3, dias
FROM (
    SELECT sensor1, sensor2, sensor3, dias, id FROM `$id` ORDER BY id DESC LIMIT 10
) t
ORDER BY id

或者，如果您运行的是 MySQL 8.0，则可以使用 ROW_NUMBER():

SELECT sensor1, sensor2, sensor3, dias
FROM (
    SELECT sensor1, sensor2, sensor3, dias, id, ROW_NUMBER() OVER(ORDER BY id DESC) rn
    FROM `$id`
) t
WHERE rn <= 10
ORDER BY id