Primary keys in practice: does an identifier “typically” use more than one attribute (i.e., is a composite key the usual case)?

Introduction / Context:
Designers often debate natural vs. surrogate keys and single-attribute vs. composite identifiers. The question claims that identifiers “typically” use multiple attributes. Understanding common practice helps produce simpler joins and clearer foreign keys.

Given Data / Assumptions:

• We are discussing general practice, not a special domain with unavoidable composites.
• Identifiers (primary keys) should uniquely identify entity instances.
• Surrogate keys (e.g., IDENTITY/sequence/UUID) are widely used.

Concept / Approach:
While composite identifiers exist (especially in associative/bridge tables or when using natural keys that require multiple columns), many schemas prefer a single-attribute primary key (often surrogate) for simplicity. Foreign keys referencing a single column ease indexing and joining, and surrogate keys avoid change-propagation when business values mutate.

Step-by-Step Solution:
Assess the “typical” case across common systems: single-column integer/UUID PKs are prevalent.Recognize exceptions: associative entities often have composite PKs of the two parent FKs.Therefore, the statement “typically uses more than one attribute” is inaccurate as a general rule.

Verification / Alternative check:
Survey popular schemas (ERP, CRM); most base tables use single-column PKs. Composite keys are concentrated in intersection tables or domains with strict natural keys.

Why Other Options Are Wrong:
Asserting composites are “most” common overgeneralizes. Tying the claim to 3NF is unrelated—normalization does not force composite PKs. Surrogate keys are single-column by nature.

Common Pitfalls:
Using wide composite PKs everywhere, complicating FKs and indexes; alternatively, overusing surrogates without enforcing natural-key uniqueness with alternate keys.

Final Answer:
Invalid statement — single-attribute identifiers are more typical