Key terminology — decide whether the following claim is correct:\n“Keys made up of two or more attributes are called composite keys.” Provide the best evaluation.

Difficulty: Easy

Correct Answer: Correct — that is the definition of a composite key

Explanation:


Introduction / Context:
Schema designers often need multiple attributes to uniquely identify a tuple. When more than one attribute participates jointly in uniqueness, the resulting key has a specific name and properties.



Given Data / Assumptions:

  • “Key” means a set of attributes that uniquely identifies rows (tuples).
  • “Composite” implies more than one component attribute.
  • We do not constrain whether the composite key is primary, alternate, or candidate.


Concept / Approach:
A composite (or compound) key is exactly a key composed of two or more attributes. It can be a candidate key or the chosen primary key. The definition does not depend on normal form, foreign keys, or whether the attributes are natural or surrogate.



Step-by-Step Solution:

Identify semantic content: “two or more attributes” → composite.Match with definition: composite key = multi-attribute key.No contradictory conditions are present.Therefore, the claim is correct.


Verification / Alternative check:
Example: Enrollment(student_id, course_id, term) might have primary key (student_id, course_id, term). This three-attribute primary key is composite.



Why Other Options Are Wrong:

  • Foreign key status is irrelevant to being composite.
  • Surrogate keys are artificial identifiers and may be single-attribute; composite does not imply surrogate.
  • Normal form level (BCNF, 3NF) is unrelated to the definition.


Common Pitfalls:
Confusing composite keys with concatenated values; assuming composite keys cannot be primary keys (they can); believing composite implies cross-table linkage (it does not).



Final Answer:
Correct — that is the definition of a composite key

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