1.4. Tables as Relationships
A relationship is shown in a table by columns that reference one or more entity tables. Without the entities, the relationship has no meaning, but the relationship can have attributes of its own. For example, a show business contract might have an agent, a studio, and a movie star. The method of payment is an attribute of the contract itself, and not of any of the three parties.
These tables will always have FOREIGN KEY references to the entities in the relationship and DRI actions to enforce the business rules.
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