It is really hard to understand what you are doing without the actual code in <code>..</code> tags. How you are accessing the DB? Your while loop as shown does nothing useful. Do you have any output at all to show?

Update: Another thought if you show your SQL statement, there may be a way so that these 'undef' columns do not even show up from the DB. I think stevieb is right that a "real" undefined value shows up instead of the string 'undef' although that may not be apparent from whatever printout you are looking at.

Just a guess at something that you might be trying to do, form a menu from an row from the DB...

#!usr/bin/perl
use warnings;
use strict;
use Data::Dumper;

use List::Pairwise qw(mapp grepp); ##need to install this module

my @ary = qw(AirDefense 2 Mobile-N-Site 4 Owl 6 undef 8);
my %hash = mapp{$a ne 'undef' ? ($b,$a):()}@ary;

foreach my $opt (sort{$a<=>$b} keys %hash)
{
    print "$opt => $hash{$opt}\n";
}
__END__
2 => AirDefense
4 => Mobile-N-Site
6 => Owl
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