Here's an example of the type of thing you could do in this situation:

use strict;
use warnings;

my @labels = qw{First: Middle: Last: Age:};
my @sql_data = (q{John}, q{}, q{Smith}, 20);
my $no_value = q{*NO_VALUE_SUPPLIED*};

my $counter = 0;

print map {
    ($labels[$counter++], qq{\t}, ($_ ne q{} ? $_ : $no_value), qq{\n}
+)
} @sql_data;
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Which produces:

First:  John
Middle: *NO_VALUE_SUPPLIED*
Last:   Smith
Age:    20
[download]

As you're new to Perl, here's a few pointers:

• Always include use strict; and use warnings; at the start of your code
• There are different operators for comparing numbers and strings - see perlop (in particular, the sections Relational Operators and Equality Operators)
• Choose more meaningful variable names (@ary and @array aren't particularly enlightening)