A minimal attribute or minimal set of attributes that can uniquely identify…
2023
A minimal attribute or minimal set of attributes that can uniquely identify each tuple in a relation, and from which a primary key may be chosen, is known as:
- A.
Primary Key
- B.
Foreign Key
- C.
Alternate Key
- D.
Candidate Key
Attempted by 2893 students.
Show answer & explanation
Correct answer: D
Answer: Candidate key
Definition: A candidate key is a minimal set of attributes that can uniquely identify each tuple (row) in a relation (table).
Key points:
1. Uniqueness: No two rows can have the same candidate-key value.
2. Minimality: No proper subset of the candidate key attributes can uniquely identify tuples.
3. Relation to primary key: One candidate key is chosen as the primary key. Candidate keys not chosen as the primary key are called alternate keys.
4. Foreign key distinction: A foreign key references a key in another table and does not by itself uniquely identify tuples in its own table.
Why this answers the question: The question asks for the minimal unique attribute set from which a primary key may be chosen. That term is candidate key.