Ternary and Higher-Order ER Diagrams
In this chapter we ﬁrst discuss how intersection attributes create ternary relationships, and then look at the structural constraints of ternary relationships. Next, we discuss how ternary and other n-ary relationships do not preclude binary relationships, and how some ternary diagrams can be resolved into binary relationships. The development of ternary relationships from relationships of relationships is also discussed. Step 6 of the ER design methodology is also redeﬁned in this chapter to include ternary and other higher-order relationships.