// you need to set $cookie_pfx to the cookie prefix

$uid = $_COOKIE[$cookie_pfx . "member_id"];
// Get the username from the id - set $prefix as the prefix without the _
$jsql = "SELECT " . $prefix . "_members.mgroup, " . $prefix . "_members.name, " . $prefix . "_members.member_login_key, ". $prefix . "_members_converge.converge_pass_hash, " . $prefix . "_members_converge.converge_pass_salt
FROM " . $prefix . "_members
LEFT OUTER JOIN " . $prefix . "_members_converge ON " . $prefix . "_members.id = " . $prefix . "_members_converge.converge_id
WHERE id = '$uid'";
$result = mysql_query($jsql) or die ($jsq);
$row = mysql_fetch_array($result);
// (I used it for more than username - thus why its a big query)
$username = $row['name'];
echo ($username);