Check if usergroup exists - php

Question

I have 2 variables which both hold comma separated lists. One is a permissions variable and the other is the usergroup list of the person wanting to access a page.
1 = user
2 = editor
3 = moderator
4 = admin
<?php
$query = mysql_query("SELECT * FROM users WHERE id='{$user['id']}'");
$user = mysql_fetch_assoc($query);
$query2 = mysql_query("SELECT * FROM menu WHERE active='1'");
$page = mysql_fetch_assoc($query2);
echo $user['usergroup']; // 1
echo $page['usergroup']; // 2,3,4
?>
I need help to find a way to compare both variables to check if they have the right usergroup to access a page
if $user['usergroup'] contains a number from $page['usergroup'] do X otherwise do Y
Thanks :)

Answer 1

$user = "1,3,5";
$page = "1,2,5";
//explode and trim for a case you have spaces '1, 2,3 ,4'
$u = array_map('trim', explode(",", $user));
$p = array_map('trim', explode(",", $page));
$intersect = array_intersect( $u, $p );
if ( count($intersect) )
{
//ok
print_r( $intersect );
}
else
{
//error
}
Allowed permissions:
Array
(
[0] => 1
[2] => 5
)

Answer 2

Try this:
$query = mysql_query("SELECT * FROM users WHERE id='{$user['id']}'");
$user = mysql_fetch_assoc($query);
$query2 = mysql_query("SELECT * FROM menu WHERE active='1'");
$page = mysql_fetch_assoc($query2);
$pageGroups = explode(',', $page['usergroup']);
if (array_search($user['usergroup'], $pageGroups) !== false) {
//TODO: User have access
}

Answer 3

Although I wouldn't store permissions as a commaseparated string, something like this might be what you are looking for:
$pageaccess = explode(',', $page['usergroup']);
if(in_array($user['usergroup'], $pageaccess)) {
// Has permissions. Code goes here.
}
edit: renamed $permissions to $pageaccess

Answer 4

While all the answers you got should work I'd like to add a comment to your approach. It's never a good idea to store comma seperated lists into your database. It offends the concept of database normalization.
Instead of storing comma seperated lists you should reconsider your database design. A possible approach could be:
users (user_id, username)
permissions(permission_id, permission)
user_permissions(up_id, permission_id, user_id)
That is much more efficient since you don't need to process the data that come from your database any further. You can just query your database and ask if the user has a certain permission.
SELECT `up_id` FROM `user_permissions` WHERE `user_id` = '{$uid}' AND `permission_id` = {5}
Taking this a step further you can assemble a little access control list:
users (user_id, username)
groups (group_id, name)
user_groups(ug_id, group_id, user_id)
permissions(permission_id, permission)
group_permissions(gp_id, group_id, permission_id)