my $id = 1;
my $data = {};
my $table1_results = $dbh->selectall_arrayref('SELECT field1 FROM table1 WHERE id = ?', {Slice => {}}, $id);
foreach my $field1 (@$table1_results) {
	$data->{$id}->{$table1_results->{field_of_interest}} = undef;
	my $table2_results = $dbh->selectall_arrayref('SELECT field2 FROM table2 WHERE field1 = ?', {Slice => {}}, $field1->{field1});
	foreach my $field2 (@$table2_results) {
		$data->{$id}->{$table1_results->{field_of_interest}}->{$table2_results->{field_of_interest}} = undef;
		...
	}
}