php runs on the server, so it is only going to run once per page load.
to update the chart without reloading the page,
you will need to separate the php from the html / javascript.
save the php to a different file, all by itself.
you need to include the rest of the data in the php,
including the column headings.
see following snippet for the php.
for example purposes, we'll name the file --> getdata.php
<?php
$servername = "localhost";
$username = "u644759843_miki";
$password = "plantaze2020!";
$dbname = "u644759843_plantazeDB";
// Create connection
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$conn = mysqli_connect($servername, $username, $password, $dbname);
$conn->set_charset('utf8mb4');
$sql = "SELECT ProductPurity FROM `Precizno ProductPurity` ORDER BY TimesStamp DESC LIMIT 1";
$result = mysqli_query($conn, $sql);
// create data array
$data = [];
$data[] = ["Label", "Value"];
// output data of each row
while($row = mysqli_fetch_assoc($result)) {
$data[] = ["ProductPurity", $row["ProductPurity"]];
}
mysqli_close($conn);
// write data array to page
echo json_encode($data);
?>
next, save the html / javascript to its own file.
for example purposes, we'll name the file --> chart.html
to get the data from php,
we'll use jquery ajax.
see following snippet...
<!DOCTYPE html>
<html lang="en">
<head>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.0/jquery.min.js"></script>
<script src="https://www.gstatic.com/charts/loader.js"></script>
<script>
google.charts.load('current', {
packages: ['gauge']
}).then(function () {
var options = {
width: 400, height: 120,
redFrom: 90, redTo: 100,
yellowFrom:75, yellowTo: 90,
minorTicks: 5
};
var chart = new google.visualization.Gauge(document.getElementById('chart_div'));
drawChart();
function drawChart() {
$.ajax({
url: 'getdata.php',
dataType: 'json'
}).done(function (jsonData) {
// use response from php for data table
var data = google.visualization.arrayToDataTable(jsonData);
chart.draw(data, options);
// draw again in 5 seconds
window.setTimeout(drawChart, 5000);
});
}
});
</script>
</head>
<body>
<div id="chart_div" style="width: 400px; height: 120px;"></div>
</body>
</html>
EDIT
need to make sure the Value column...
is a number --> 99.9594
not a string --> "99.9594"
you can convert using --> (float)
// output data of each row
while($row = mysqli_fetch_assoc($result)) {
$data[] = ["ProductPurity", (float) $row["ProductPurity"]];
}
and / or use the JSON_NUMERIC_CHECK constant on the encode statement...
echo json_encode($data, JSON_NUMERIC_CHECK);
