php - How to use 'time'(来自数据库的数据，数据类型: timestamp ) for plotting graph in Chart JS

Question

传感器设备(温度传感器)每 10 秒向数据库发送一次数据。我必须绘制一天时间和温度之间的图表(最新数据)。我设法从数据库中获取数据。问题是因为我有大量的时间数据以及如何使用它来标记 Y 轴。日期和时间的格式为 2019-04-09 12:28:36。但我可以提取时间。但仍然如何在一个 (Y) 轴上使用时间。我的代码显示错误 Uncaught SyntaxError: Unexpected token :

//PHP

$sql = "SELECT TIME(Date_Time) as TIME , Temperature FROM dataTable WHERE Date_Time>= (CURDATE() - INTERVAL 1 DAY )  ORDER BY Date_Time DESC ";

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

   while($row = $result->fetch_assoc()) {
     $tempValue =$row['Temperature'];
     $timeInterval=$row['TIME'];

     $tempValues =$tempValues. $tempValue. ',';
     $timeIntervals =$timeIntervals. $timeInterval. ',';
    }
$tempValues =trim ($tempValues, ",");
$timeIntervals= trim ($timeIntervals,"," );

//Javascript

var myChart = document.getElementById('myChart').getContext('2d');




        var data = {
            datasets: [{

            data: [<?php  echo $tempValues ?>],
            backgroundColor: 'transparent',
            borderColor:'rgba(255,99,132)',
            borderWidth:5,
            label: 'Temperature in degree'
          }],

//error in the following line !
          labels: [<?php  echo $timeIntervals ?>]
        };

        var particleChart =new Chart(myChart, {
          type:'line',
          data: data
        });

Answer 1

标签必须是字符串。以这种方式构建 $timeIntervals...

$timeIntervals = $timeIntervals . '"' . $timeInterval . '",';

...为了将日期时间值括在双引号之间。