How to create Chart with 2 variables (x,,y) - php

Question

I am looking forward chart like this https://i.stack.imgur.com/a6dAq.png with this code
php + html:
$sql = "SELECT val1 , val2 ,t
FROM DvojeHodnoty
INNER JOIN Pristroje ON DvojeHodnoty.dev_name = Pristroje.dev_name
WHERE t>'$startdate2' AND t< '$enddate2' AND Pristroje.nazev_pristroje='$pristroj' order by val1 asc;";
$result = mysqli_query($connection, $sql);
while ($row = mysqli_fetch_array($result))
{
$t = $t.'"'.date('d.m.y H:i:s', $row['t']/1000).'",';
$hodnota = $hodnota.'"'.$row['val1'].'",';
$hodnota2 = $hodnota2.'"'.$row['val2'].'",';
}
$start = date('d.m.y', $startdate2/1000);
$end = date('d.m.y', $enddate2/1000);
$t = trim($t,",");
$hodnota = trim($hodnota,",");
$hodnota2 = trim($hodnota2,",");
}
<div id="chart-container" style="background: white">
<canvas id="chart"></canvas>
<script>
var ctx =document.getElementById("chart").getContext('2d');
var myChart = new Chart(ctx, {
type:'line',
data: {
labels: [<?PHP echo $hodnota2; ?>],
datasets:
[
{
label: '<?PHP echo $start;?> - <?PHP echo $end; ?> Přístroj: <?PHP echo $pristroj;?> ',
data: [<?PHP echo $hodnota; ?>],
backgroundColor:'transparent',
borderColor:'rgba(255,99,132)',
borderWidth: 3
}]
},
options: {
scales: {
yAxes:[{
scaleLabel: {
display: true,
labelString: 'σ',
fontSize: 20
}
}],
xAxes:[{
scaleLabel: {
display: true,
labelString: 'ε',
fontSize:20
}
}]
}
}
})
</script>
</div>
but so far I got only this https://i.stack.imgur.com/Ri8Ho.png.
I don't know how to create chart with two variables, I tried scatter but so far I am stuck with no ability to create graph with x,y line as values. Is there any easy way to create chart with two variables? If so can you help me/ give me some documentation? (I've seen one scatter chart with fix values, but I am not able to do it with php echo (with values from database) since I need to have variable values since user will choose values depends on chosen date. So far I got only 1 value (y) and two values but with text (numbers counted as text not as value) so chart looks weirdly (0,1,-1 still on same line not like normal graph showned up).

Answer 1

The problem was that data type was VARCHAR and for sorting it I need INT. Problem solved