Does the “degree” of a relationship indicate the number of participating entity types (for example, unary = 1, binary = 2, ternary = 3)?

Introduction / Context: Relationship degree is a classic ER concept distinct from cardinality. Degree counts how many entity types participate. Most operational schemas are built from binary relationships, but unary (recursive) and ternary (three-way) relationships occur in practice.

Given Data / Assumptions:

• Unary: one entity type relates to itself (e.g., Employee manages Employee).
• Binary: two entity types (e.g., Customer places Order).
• Ternary: three entity types (e.g., Doctor prescribes Drug to Patient).

Concept / Approach: Degree answers “how many entity types?” while cardinality answers “how many instances on each side?” and optionality answers “minimum participation required?” Keeping these distinct helps avoid modeling errors.

Step-by-Step Solution: Identify participants in a relationship. Count the distinct entity types to determine degree. Separately specify maximum and minimum cardinalities for each participating side.

Verification / Alternative check: Transform a ternary relationship into associative tables; verify that the relationship truly requires three-way dependency, not two separate binaries.

Why Other Options Are Wrong: “Incorrect” conflicts with accepted definitions. Limiting to binary or tying to optionality mixes separate properties.

Common Pitfalls: Forcing ternary relationships into binary pairs without preserving semantics; conflating degree with cardinality.

Final Answer: Correct