ModelBusiness logic goes hereViewPresentation logic goes hereControllerApplication logic goes hereHere's a typical bit of "controller" logic: sub add_product_to_order { my ( $dbh, $p_id, $o_id ) = @_; unless ( $o_id && $o_id =~ /^\d+$/ ) { dienice("Bad order number $o_id"); } my $o_sql = 'SELECT * FROM orders WHERE id = ?'; my $p_sql = 'SELECT * FROM products WHERE id