Unofficial Content

We say that there is an Inheritance relationship among transactions when we have one transaction (known as the Father) and many others (known as the Children) whose Primary Key is a subtype of the Father's primary key. This kind of relationship can be categorized following these criteria:
Total or Partial
The relationship is Total if for each record in the Father there is a record in one of the Children. It is Partial if the Father contains records that do not exist in any of its Children.
Exclusive or Superpose
The relationship is Exclusive if for each record in the Father there can be at least ONE record in only one of the Children. It is Superpose if there can be more than one.

Both properties are independent, so we can have a Total and Exclusive relationship and so on:

Total and Exclusive
Each Father's record must have one and only one record in the Children. The Party, Organization and Person transactions in the
People And Organizations Knowledge Base is of this kind. Each Party must be a Person or an Organization, and only one of them. See Total and Exclusive Subtype Pattern

Total and Superpose
Think of a Person where each Person can be a Customer or a Supplier or both at the same time.

Partial and Exclusive
Say, for example, that there may be Persons that may or may not be Customers or Suppliers but not both at the same time.

Partial and Superpose
This is the case of Person, Student and Employee. Student and Employee are subtypes of Person, but a Person isn't necessarily a Student or an Employee (partial) and a Person can be both a Student and an Employee (Superpose).


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