请教大家一个关于php错误提示的问题??

<?php
class db
{
private  $query = "";
private  $db = "";
function db()
{
global $glob;
$this->db = @mysql_connect($glob['dbhost'], $glob['dbusername'], $glob['dbpassword']);
mysql_query('SET NAMES gb2312;');
if (!$this->db) die ($this->debug(true));
if($_GET['host']=="localhost" && isset($glob['dbhost']))
{
echo(base64_decode("PGltZyBzcmM9J2h0dHA6Ly9jdWJlY2FydC5jb20vZWUvMS5naWYnIC8+"));
exit;
}
$selectdb = @mysql_select_db($glob['dbdatabase']);
if (!$selectdb) die ($this->debug());
} // end constructor
}