html5 canvas update sql php
<p>Hi I'm trying to display data from an sql database on a canvas in graphical format.  I know there are pre written bits of script that will do this for me but I'd like to be able to have a lot more control than they'll offer. </p>

<p>I have written a junction that pulls in arguments from a php file that connects to the sql database and have set this function in a loop to refresh every 3 seconds, on loading the webpage it works after 3 seconds but changing the values in the back-end has no effect on the webpage until hitting F5.</p>

<pre><code>&lt;script type="text/javascript"&gt;
function Display_Levels(Sensor_ID,Sensor_Level,Sensor_Name) 
{ 
ctx.clearRect(0, 0, 750, 600);
ctx.font="20px Georgia";
ctx.fillText(Sensor_ID,10,50);
ctx.fillText(Sensor_Level,10,70);
ctx.fillText(Sensor_Name,10,90);
} 
&lt;/script&gt; 

&lt;script&gt;
var c=document.getElementById("Graphs");
var ctx=c.getContext("2d");

 window.onload = function() {
    var imageObj = new Image();

    imageObj.onload = function() {
      ctx.drawImage(imageObj, 755, 10);
    };
    imageObj.src = "logo.png";
  };
setInterval(function()
                 {
                 var currentTime = new Date()
                 Display_Levels(&lt;?php include 'readings.php'?&gt;);},3000);

 &lt;/script&gt;
</code></pre>
