update mysql datatable using checkbox in loop form - php

Question

i'm trying to update a custom table for my wordpress plugin, first im getting the roles from my table then display it using a form and this works fine, now the problem is that when i check the boxs it update in database, but when i uncheck it, it dont update at all and if i uncheck it all i get this error message
Warning: Invalid argument supplied for foreach() in C:\wamp\www\wp_test\wp-content\plugins\Data\settings.php on line 52
<?php
$roles=get_editable_roles();
global $wpdb;
$table_name = $wpdb->prefix. "Author_detailed_repport";
?>
<h3>Settings Page</h3>
<h4>Add/Remove a role from filter list</h4>
<p>This setting allow you to add/remove roles from the filter<br />
list, here down a list of all the roles existing in your website, all<br />
you have to do is to check/uncheck wich you wanna add/rmove from filter list</p>
<form action="<?php $_REQUEST['PHP_SELF'] ?>" method="post">
<?php
require_once('../wp-config.php');
$i=0;
foreach($roles as $role)
{
$rom=$role['name'];
$results = $wpdb->get_results( "SELECT * FROM ".$table_name." WHERE role= '".$rom."'" );
if ($results==NULL)
{$wpdb->insert( $table_name, array(
'role' => $role['name'],
'statut' => '',
'post_number' => '',
'activate' => ''
));
}?>
<input type="checkbox" name="cat[]" value="<?php echo $i+1 ;?>" <?php checked($results[0]->statut, $i+1); ?> />
<input type="hidden" name="ww" value="0">
<?php
?>
<label>
<?php echo $results[0]->role;?></label><br />
<?php $i++; } ?>
<input type="submit" value="save" name="saveme" />
</form>
<?php
if(isset($_POST['saveme']))
{
$cats=$_POST['cat'];
foreach($cats as $cam)
{
if(isset($cam))
{
$wpdb->update( $table_name, array(
'statut' => $cam
),array('ADR_id' => $cam),array('%d'));}
else
{
$wpdb->update( $table_name, array(
'statut' => '0'
),array('ADR_id' => $cam),array('%d'));
}
}
}
?>

Answer 1

Because $roles is not set yet and there you need to do a another check
If(isset($roles)) {
//foreach loop goes in here
}