MySQL错误最大用户在线

Question

什么不好？

public function __construct($host, $user, $password, $database)
    {    
        $this->_connection = mysql_pconnect($host, $user, $password) or die( mysql_error( ) );
        if ( !$this->_connection )
        {
            throw new Exception(mysql_error( ));

    }
    mysql_select_db( $database, $this->_connection );
    if ( mysql_error() )
    {
        throw new Exception(mysql_error( ) );
        }

    }

如果我有超过20个在线用户，我有错误max_user_online ...