while (($key,$value) = each %$DB_name) {

##</code><code>##

   my %name_to_hash = (
      ISWTEST => \%ISWTEST,
      ISWLIVE => \%ISWLIVE,
      #...);
   while (($key,$value) = each %{$name_to_hash{$DB_name}}) {
      #...