Remove One Dependency Problem at a Time

First normal form gives each cell one value, splitting an order's product list into one row per product. Second normal form requires 1NF and removes dependencies on part of a candidate key, such as a product_name that depends only on product_id in a table keyed by (order_id, product_id). Third normal form requires 2NF and removes non-key facts that depend on other non-key facts, such as a customer_city determined by customer_id.