A functional dependency can be tested easily on a materialized view using…
2023
A functional dependency can be tested easily on a materialized view using which constraint combination?
- A.
Primary key
- B.
NULL
- C.
UNIQUE
- D.
NOT NULL and UNIQUE
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Correct answer: D
Correct answer: NOT NULL and UNIQUE
To test a functional dependency on a materialized view, the determinant attributes must identify rows without duplicates and without missing values.
UNIQUE: prevents duplicate determinant values.
NOT NULL: prevents missing determinant values.
Why not only primary key: a primary key is a specific key declaration. The question asks for the constraint combination used for the test, and the required combination is explicitly NOT NULL plus UNIQUE.
Therefore, the best answer is NOT NULL and UNIQUE.