my @chain = get_chain($employee);
foreach my $emp (@chain) {
    print $emp->{name}, qq{\n};
}
sub get_chain {
    my ($e_id) = @_;

    # Assumes that id is the employee id field, 
    #   and supervisor is also an employee id.
    my $en_select =
      q{SELECT name, supervisor FROM employee 
          WHERE ( id = ? ) LIMIT 1;};
    my $ens = $dbh->prepare($en_select);
    my $enr = $ens->execute($e_id) or die $dbh->errstr;

    my %link = ( id => $e_id, );
    my @row_enr = $ens->fetchrow_array;
    $link{name} = $row_enr[0];
    if ( defined $row_enr[1] and $row_enr[1] != $e_id ) {
        $link{supervisor} = $row_enr[1];
        return ( get_chain( $link{supervisor} ), \%link );
    }
    else {
        return ( \%link );
    }
}