$sth -> execute(
     $self -> param('catalog_id'),
     0 + $start_item,
     20
 );

##</code><code>##

$sth->bind_param(1, $self->param('catalog_id'), SQL_INTEGER);
$sth->bind_param(2, $start_item, SQL_INTEGER);
$sth->bind_param(3, 20, SQL_INTEGER);
$sth->execute();