A VIP report wants «the two most expensive orders per customer» — for each customer separately, their top two by amount. Numbered windows solve this trivially, but there's a more expressive trick: a join where a limited subquery sees the outer row's columns and runs separately for each of them. Build the report without window functions — for every customer show the customer id, the order id, and the amount, limited to the two largest orders per customer. Sort by customer id, ties broken by amount descending.