One option in deduplication is usually a hash:

my %cats;
while (my $pointer = $sth->fetchrow_hashref) {
    $cats{$pointer->{category}} = 1;
}
for my $category (keys %cats) {
    print "$category\n";
}

[download]

See also the FAQ How can I remove duplicate elements from a list or array?

Update: typo now fixed (line 3 was $cat{...}). Thanks wjw for spotting.

In reply to Re: Printing Categories from SQL search by hippo
in thread Printing Categories from SQL search by htmanning

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