What version of Perl are you using? This works for me:

    #!/usr/bin/perl -w
    use strict;

    my $sortname = shift;
    print join ' ', sort $sortname 1..20;

    sub num { $a <=> $b }
    sub alpha { $a cmp $b }
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Save this as foo.pl, and...

    % foo.pl num
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

    % foo.pl alpha
    1 10 11 12 13 14 15 16 17 18 19 2 20 3 4 5 6 7 8 9
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This is consistent w/ the sort docs:

    SUBNAME may be a scalar variable name
    (unsubscripted), in which case the value provides
    the name of (or a reference to) the actual subroutine
    to use.  In place of a SUBNAME, you can provide a
    BLOCK as an anonymous, in-line sort
    subroutine.
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However, I do seem to remember running into your situation in the past. I don't know what version of Perl I was using then; probably 5.004 or some such. I'm now using 5.005_03, which could explain it.

If you are using a real database, though, I would suggest that you try using "order by", as it's likely to be faster than anything you can do yourself, particularly if you have your columns indexed.