my %table;
$table{type_of_animal} = "giraffe";

##</code><code>##

my $row = $sth->fetchrow_arrayref;
$row->[0] =~ s/\$(\w+)/exists $table{$1} ? $table{$1} : "\$$1"/eg;

##</code><code>##

{
   no strict 'refs';
   my $row = $sth->fetchrow_arrayref;
   $row->[0] =~ s/\$(\w+)/$$1/eg;
}