use DBI; my $dbh = DBI->connect(...);

    ....

    my @ids = ();

    my $sth = $dbh->prepare('select id from items where '--PREDICATE--');

    $sth->execute();
    while (my ($id) = $sth->fetchrow_array()) {
        push @ids, $id;
    }

    $sth->finish();

    ....