60. Composite UNIQUE (Scenario 2)

DBMS Published 30 Sept 2026 Updated 30 Sept 2026 0 Views Verified

Prevent duplicate product/category combinations.

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Answer & Explanation

4 Answers

Verified Correct Answer

Option A

ALTER TABLE products ADD CONSTRAINT uq_product_category UNIQUE (name, category_id);

Additional Explanation

Correct implementation. Prefer parameterized queries in application code, validate affected rows for UPDATE/DELETE, and use transactions for related writes.

Verified

Option B

Use a DELETE statement instead.

Additional Explanation

This option is incorrect for the stated requirement.

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Option C

Use a SELECT without a constraint.

Additional Explanation

This option is incorrect for the stated requirement.

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Option D

Use a CHECK for the same relationship.

Additional Explanation

This option is incorrect for the stated requirement.