sub query_databases {
....
 return \%dbs;
}

##</code><code>##

my $dbsref = query_databases ();

##</code><code>##

my $result = do_compare( $dbsref );

##</code><code>##

sub do_compare {
  my $dbsref = shift;
  for my $key ( keys %$dbsref ) {
    if ($dbsref->{$key}{ORACLE1} eq $dbsref->{$key}{ORACLE1}) {
        # the same
    } else {
        # different
    }
  }
 }