title: Pass multiple variables to AJAX onchange select
body: <p>I am looking at this script from W3schools.com (Ajax, PHP and Mysql)
  <a href="http://www.w3schools.com/php/php_ajax_database.asp" rel="nofollow">http://www.w3schools.com/php/php_ajax_database.asp</a></p>
  
  <pre><code>&lt;html&gt;
  &lt;head&gt;
  &lt;script type="text/javascript"&gt;
  function showUser(str)
  {
  if (str=="")
    {
    document.getElementById("txtHint").innerHTML="";
    return;
    } 
  if (window.XMLHttpRequest)
    {// code for IE7+, Firefox, Chrome, Opera, Safari
    xmlhttp=new XMLHttpRequest();
    }
  else
    {// code for IE6, IE5
    xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
    }
  xmlhttp.onreadystatechange=function()
    {
    if (xmlhttp.readyState==4 &amp;&amp; xmlhttp.status==200)
      {
      document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
      }
    }
  xmlhttp.open("GET","getuser.php?q="+str,true);
  xmlhttp.send();
  }
  &lt;/script&gt;
  &lt;/head&gt;
  &lt;body&gt;
  
  &lt;form&gt;
  &lt;select name="users" onchange="showUser(this.value)"&gt;
  &lt;option value=""&gt;Select a person:&lt;/option&gt;
  &lt;option value="1"&gt;Peter Griffin&lt;/option&gt;
  &lt;option value="2"&gt;Lois Griffin&lt;/option&gt;
  &lt;option value="3"&gt;Glenn Quagmire&lt;/option&gt;
  &lt;option value="4"&gt;Joseph Swanson&lt;/option&gt;
  &lt;/select&gt;
  &lt;/form&gt;
  &lt;br /&gt;
  &lt;div id="txtHint"&gt;&lt;b&gt;Person info will be listed here.&lt;/b&gt;&lt;/div&gt;
  
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>This shows a simple select with 4 values.</p>
  
  <p>And this is the PHP script.</p>
  
  <pre><code>&lt;?php
  $q=$_GET["q"];
  
  $con = mysql_connect('localhost', '*', '*');
  if (!$con)
    {
    die('Could not connect: ' . mysql_error());
    }
  
  mysql_select_db("ajax_demo", $con);
  
  $sql="SELECT * FROM user WHERE id = '".$q."'";
  
  $result = mysql_query($sql);
  
  echo "&lt;table border='1'&gt;
  &lt;tr&gt;
  &lt;th&gt;Firstname&lt;/th&gt;
  &lt;th&gt;Lastname&lt;/th&gt;
  &lt;th&gt;Age&lt;/th&gt;
  &lt;th&gt;Hometown&lt;/th&gt;
  &lt;th&gt;Job&lt;/th&gt;
  &lt;/tr&gt;";
  
  while($row = mysql_fetch_array($result))
    {
    echo "&lt;tr&gt;";
    echo "&lt;td&gt;" . $row['FirstName'] . "&lt;/td&gt;";
    echo "&lt;td&gt;" . $row['LastName'] . "&lt;/td&gt;";
    echo "&lt;td&gt;" . $row['Age'] . "&lt;/td&gt;";
    echo "&lt;td&gt;" . $row['Hometown'] . "&lt;/td&gt;";
    echo "&lt;td&gt;" . $row['Job'] . "&lt;/td&gt;";
    echo "&lt;/tr&gt;";
    }
  echo "&lt;/table&gt;";
  
  mysql_close($con);
  ?&gt;
  </code></pre>
  
  <p>Now I understand what it does and how it works, but let's say that I want to pass 3 more variables to the PHP script, when someone changes the value of the selectbox, how do I do that??</p>