product_units (product_id, product_name, units_sold) has this month's sales. The newsletter features the top 3 products by units sold — but it must not drop a product that sold exactly as many as one that made the list.
A product makes the list when fewer than 3 products sold more than it did. (If two products tie for third, both are in, so the list can be longer than 3; but a product behind them doesn't sneak in.)
Columns: product_id, product_name, units_sold. Sort by units_sold, highest first, then by product_id.