Unable to connect to database server!?多谢

[qing_zb]

// define our database connection

//数据库是用phpmyadmin建的，在mysql的data下有数据库catalog
//下面是部分代码
define('DB_SERVER', 'localhost');
define('DB_SERVER_USERNAME', 'root');
define('DB_SERVER_PASSWORD', '');
define('DB_DATABASE', 'catalog');
define('USE_PCONNECT', 1);

//==========
function tep_db_connect() {
global $db_link;

if (USE_PCONNECT) @$db_link = mysql_pconnect(DB_SERVER, DB_SERVER_USERNAME, DB_SERVER_PASSWORD);
else @$db_link = mysql_connect(DB_SERVER, DB_SERVER_USERNAME, DB_SERVER_PASSWORD);

if ($db_link) @mysql_select_db(DB_DATABASE);
return $db_link;
}