specify an order. (The scalar ref causes it to be passed as raw sql to the DB,
so you will need to manually quote things as appropriate.)
+If your L<SQL::Abstract> version supports it (>=1.50), you can also use
+C<{-desc => 'year'}>, which takes care of the quoting for you. This is the
+recommended syntax.
+
=head2 columns
=over 4