9 Ternary and Higher-Order ER Diagrams
9.1 INTRODUCTION
All relationships we have dealt with so far have been binary relationships. Although binary relationships seem natural to most of us, in reality it is sometimes necessary to connect three or more entities. If a relationship connects three entities, it is called a ternary or 3-ary relationship. If a relationship connects more than three entities (n entities), it is called an n-ary relationship, where n equals the number of entities participating in the relationship. The n-ary relationships (n ≥ 3) are also referred to as higher-order relationships.
In this chapter, we consider relationships to connect three or more entities. First, we look at ternary ...
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