my $asdf = $dbh->selectall_hashref($sth, ['blah1','blah2','blah3']);

        my ($key1, $key2, $key3);

        foreach $key1 (keys %{$asdf}) {
                foreach $key2 (keys %{$asdf->{$key1}}) {
                        foreach $key3 (keys %{$asdf->{$key1}->{$key2}}) {

# Do something here...

                         }        
                }
        }