Pagination only returning first page values - php

Question

For the past 2 days I've been looking for a pagination script of sorts, and I found this one which I'm starting to implement on my website.
The code is the following:
<?php
if (!(isset($pagenum)))
{
$pagenum = 1;
}
$data = mysqli_query($lig,"SELECT * FROM requisicao") or die("data");
$rows = mysqli_num_rows($data);
$page_rows = 5;
$last = ceil($rows/$page_rows);
if ($pagenum < 1)
{
$pagenum = 1;
}
elseif ($pagenum > $last)
{
$pagenum = $last;
}
$max = 'limit ' .($pagenum - 1) * $page_rows .',' .$page_rows;
$data_p = mysqli_query($lig,"SELECT * FROM requisicao $max") or die("data_p");
while($info = mysqli_fetch_assoc( $data_p ))
{
?>
<tr>
<td><?php print $info['id_requisicao']; ?> </td>
<td><?php print $info['username']; ?> </td>
<td><?php print $info['nome_servico']; ?> </td>
<td><?php print $info['data_requisicao']; ?> </td>
<td><?php print $info['estado_requisicao']; ?> </td>
<td><?php print $info['prioridade']; ?> </td>
<td><?php print $info['total']; ?> </td>
<td align="center">+</td>
<tr>
<?php
}
?>
</tbody>
</table>
<?php
if ($pagenum == 1)
{
}
else
{
echo " <a href='{$_SERVER['PHP_SELF']}?pagenum=1'> <<-Início</a> ";
echo " ";
$previous = $pagenum-1;
echo " <a href='{$_SERVER['PHP_SELF']}?pagenum=$previous'> <-Anterior</a> ";
}
echo " ---- ";
if ($pagenum == $last)
{
}
else {
$next = $pagenum+1;
echo " <a href='{$_SERVER['PHP_SELF']}?pagenum=$next'>Seguinte -></a> ";
echo " ";
echo " <a href='{$_SERVER['PHP_SELF']}?pagenum=$last'>Última ->></a> ";
}
?>
I'm getting the first 5 rows out of it, but when I press Seguinte (which is Next) it changes the link (TO PAGE 2) but it doesn't change the values that get outputed. Basically, it always shows page 1.
I've also looked into several similar questions but I haven't found solutions that fix my problem.
Thanks in advance, and my apologies if this is a simple problem and I'm just overlooking things :s

Answer 1

The problem is that $pagenum will be initialized as 1, anyway.
Instead of:
if (!(isset($pagenum)))
{
$pagenum = 1;
}
Try writing this:
if (!isset($_REQUEST['pagenum']) || !is_int($_REQUEST['pagenum']))
{
$pagenum = 1;
} else {
$pagenum = (int)$_REQUEST['pagenum'];
}
You may find some more info handling HTTP Request variables here