Model What the Store Must Remember
This course follows one running example: a small online store that sells products to customers, and design starts by deciding what that store needs the database to remember. An entity is a person, thing, place, or event that the database remembers with its own identity. An attribute is a fact stored about that entity. In this store, Customer, Product, and Order are entities, while a customer's name and city are Customer attributes.
The store needs to remember when each order was placed. Where should ordered_at go?