AJAX return PHP data to page - php

Question

Edit
I've changed my approach based on some research, and I'm getting a partial result.
Database:
+--------------------------------------------------+
| id | date |  objet | contenu | lu |
+--------------------------------------------------+
| 1 | 2013-01-20 | msg1 | msg1_content | 0 |
| 2 | 2013-01-20 | msg2 | msg2_content | 0 |
| 3 | 2013-01-20 | msg3 | msg3_content | 0 |
+--------------------------------------------------+
Link:
View'
JS/AJAX:
function markAsRead(id)
{
$.ajax(
{
type: "GET",
url: 'php/messagerie.php',
data: "id=" + id, // appears as $_GET['id'] # ur backend side
success: function(data)
{
// data is ur summary
$('#contenu').html(data);
}
});
}
PHP (php/messagerie.php)
$q = intval($_GET['id']);
// connect to db (of course not shown here)
if (!$con)
{
die('Could not connect: ' . mysqli_error($con));
}
$sql="SELECT * FROM coq_messagerie WHERE id = '".$q."'";
$lu = mysqli_query($mysqli, "UPDATE ".DB_PREFIX."messagerie SET lu='1' WHERE id='$q' LIMIT 1");
$result = mysqli_query($con,$sql);
echo "<table border='1' width='100%'>
<tr>
<th>id</th>
<th>date</th>
<th>objet</th>
<th>contenu</th>
<th>lu</th>
</tr>";
while($row = mysqli_fetch_array($result))
{
echo "<tr>";
echo "<td>" . $row['id'] . "</td>";
echo "<td>" . $row['date'] . "</td>";
echo "<td>" . $row['objet'] . "</td>";
echo "<td>" . $row['contenu'] . "</td>";
echo "<td>" . $row['lu'] . "</td>";
echo "</tr>";
}
echo "</table>";
mysqli_close($con);
I'm currently only retrieving only the <th>'s and not information when I'm looking up for id 2 or 3, but am getting information for id 1. How can this be only partially working?
Introduction
In an attempt to show dynamic information on my page, I'm using a mix of a few bits and pieces of code which should collect data from a basic HTML link which parses and returns data on the current page. Of course, this seems very basic, but being my first AJAX script, I would greatly appreciate some help.
Code
HTML Link:
$output .= '<a onclick="markAsRead('.$message['id'].'); return false;">'.View.'</a>';
Note: The link collects the id field as expected.
JS/AJAX Code:
function markAsRead(str) {
console.log("starting");
if (str=="")
{
console.log("string empty");
document.getElementById("contenu").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()
{
console.log("on ready state change");
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
document.getElementById("contenu").innerHTML=xmlhttp.responseText;
}
else
{
console.log("seems to returning information");
var abc = "<h1>Huh.</h1>";
document.getElementById("contenu").innerHTML=abc;
}
}
xmlhttp.open("GET","php/messagerie.php?q="+str);
xmlhttp.send();
}
Note: The console.log('###_'+str) is used to see where the code crashes. All logged properly (105, 107, 109).
PHP (php/read.php)
// connect to db (of course not shown here)
$message = $GET["messageid"];
$lu = mysqli_query($mysqli, "UPDATE messages SET lu='1' WHERE id='$message' LIMIT 1");
if(!$lu)
{
echo "Update error";
exit;
}
else
{
$data = mysqli_query($mysqli, "SELECT * FROM messages WHERE id='$message' LIMIT 1");
while($row = mysqli_fetch_array($data))
{
echo $row["contenu"];
}
}
Note: $lu is updated, which makes me believe the problem is either in the while/echo area or in my AJAX return.
Current console logs
starting
on ready state change
seems to returning information
-> GET ***/php/messagerie.php?q=3
** params -> q 3 **
** empty response **
** empty HTML **
on ready state change
seems to returning information
on ready state change
Where am I going wrong?

Answer 1

$message = $GET["messageid"];
should be
$message = $_GET["messageid"];

Answer 2

Solution found! This updates the field value to mark message as read and shows the message in the proper div.
Solution
In the AJAX request, the missing parameter of true has been added with the query.
Complete code
AJAX
function markAsRead(str)
{
if (str=="")
{
document.getElementById("contenu").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 && xmlhttp.status==200)
{
document.getElementById("contenu").innerHTML=xmlhttp.responseText;
}
}
xmlhttp.open("GET","php/messagerie.php?q="+str,true); // added ",true"
xmlhttp.send();
}
PHP
$q = intval($_GET['q']);
$con = mysqli_connect('','','',''); // values hidden here for obvious reasons
mysql_set_charset('utf8',$con);
if (!$con)
{
die('Could not connect: ' . mysqli_error($con));
}
$sql="SELECT * FROM messages WHERE id = '".$q."'";
$result = mysqli_query($con,$sql);
$update = mysqli_query($con, "UPDATE messages SET lu='1' WHERE id='$q'");
if(mysqli_num_rows($result) > 0)
{
echo "<table border='1'>
<tr>
<th>id</th>
<th>date</th>
<th>objet</th>
<th>contenu</th>
<th>lu</th>
</tr>";
while($row = mysqli_fetch_array($result))
{
echo "<tr>";
echo "<td>" . $row['id'] . "</td>";
echo "<td>" . $row['date'] . "</td>";
echo "<td>" . $row['objet'] . "</td>";
echo "<td>" . $row['contenu'] . "</td>";
echo "<td>" . $row['lu'] . "</td>";
echo "</tr>";
}
echo "</table>";
}
mysqli_close($con);