How to Build a Business Rules Engine

relationship. When used like this, “one-to-many” is probably more often intended

to convey which is the parent entity and which is the child entity in the relationship,

rather than what cardinality or optionality apply.

Subtype Relationships

Another important concept implemented in IDEF1X is the subtype relationship. This

models a situation where an entity exists as a number of different categories, all of

which are somewhat different in terms of the nonkey attributes they can contain.

Figure 3.4 further refines the example in Figure 3.3.

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CHAPTER THREE Data Modeling and Database Design

Credit Card Account

Credit Card Account Number

Date Account Opene ...