class Usuarios
{
    public function  __construct() {
        $dbhost = '*******';
        $dbuser = '*******';
        $dbpass = '*******';
        $dbname = '*******';

        mysql_connect($dbhost, $dbuser, $dbpass);

        mysql_select_db($dbname);
    }

    public function buscarUsuario($nombreUsuario){
        $datos = array();

        $sql = "SELECT * FROM guestbook WHERE title LIKE '%$nombreUsuario%' ORDER BY title ASC

        LIMIT " . ( ( (int)$_GET['page'] - 1 ) * $messaggi ) . "," . $messaggi;

        $resultado = mysql_query($sql) or die("Impossibile eseguire la query" .mysql_error());

        while ($row = mysql_fetch_array($resultado, MYSQL_ASSOC)){
            $datos[] = array("value" => $row['title']);
        }

        return $datos;
    }
}

$usuario = new Usuarios();

echo json_encode($usuario->buscarUsuario($_GET['term']));