Ultimi 10 post di un forum: ma dove sbaglio

[MasterX]

cia a tutti. volevo porvi una questione semplice.
ho fatto questo breve codice; mi dite dove sbaglio:

<?php 
class lastposts
{ 
  
  var $hostname = "localhost"; 
    var $username = "root"; 
    var $password = ""; 
   var $dbName = "my_db"; 

  function connect_db() 
  { 
    mysql_connect($this->hostname,$this->username,$this->password) 
      || die(mysql_error()); 
    @mysql_select_db($this->dbName) 
      || die("Could not connect to the database."); 
  } 

  function disconnect_db() 
  { 
    mysql_close(); 
  } 

  
} // End class 


$obj = new lastposts; 

$obj->connect_db(); 
$question = "SELECT * phpbb_topics WHERE forum_id =1 order by topic_id desc  LIMIT 0 , 10 "; 
    
    $query = mysql_query($question); 

    echo ($query); 

$obj->disconnect_db(); 
?>