Relationships (1:1, 1:N, M:N)

A real e-commerce schema isn't a pile of independent tables. Customers have orders, orders have items, items reference products, products belong to categories, customers have a shipping address. Modeling these links is what turns a database from a set of disconnected lists into something an application can actually query. This lesson covers how EF Core represents the three relationship cardinalities (one-to-one, one-to-many, many-to-many), how to declare them with both conventions and the Fluent API, and how to control what happens to children when a parent is deleted.