GATE CS 2014 Set 3 Q22 — Integrity Constraints

In relational database design, attributes of a relation schema $R$ are classified based on their participation in candidate keys:

• Prime Attribute: An attribute that is a part of at least one candidate key of $R$. That is, it appears in some candidate key of $R$.
• Non-prime Attribute: An attribute that does not appear in any candidate key of $R$.

Let's evaluate the options:

• Option A: Incorrect. An attribute does not need to be present in every candidate key to be prime; being part of any single candidate key is sufficient.
• Option B: Correct. This is the standard definition of a prime attribute.
• Option C: Incorrect. Foreign keys represent referential constraints and are independent of whether an attribute is prime.
• Option D: Incorrect. A primary key is just one chosen candidate key. Prime attributes can belong to any candidate key of the relation.