There are also lots of optimizations (and/or shorter code) that could be implemented... example:
<?php
/// Include Admin Page Here ///
include('inc/connect.php');
$user = mysql_real_escape_string($_SESSION['username']);
$sql = "SELECT u.member member, s.level level FROM users u LEFT JOIN userstats s ON u.username = s.username WHERE u.username = '$user' LIMIT 1";
$exec = mysql_query($sql);
if(($data = mysql_fetch_assoc($exec)) !== FALSE)
{
extract($data);
}
else
{
// display error message here - username not found in database
}
$addrate = .005;
$rate = $level * $addrate + ($member ? 1 : .50);
Mainly note that a) there's no need to run separate queries when the data is related - use JOINs where applicable, and b) no sense in constructing a while() loop if you only expect at most one row to be returned.