Question

Which operator can make a tuple relational query as an unsafe query?

• A. AND
• B. OR
• C. IMPLIES
• D. NOT

Hint:

NOT can produce infinite results — always check domain of attributes.

Answer 1

The Correct Option is D

The NOT operator can result in queries referencing tuples not in the database (domain variables), leading to unsafe queries.
Unsafe queries return results not bound by database contents.