704. COALESCE city — edge case 1

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

Write a MySQL query that handles NULL correctly. Avoid accidental three-valued-logic bugs.

Looking for the latest Sarkari Result 2026 updates? Check the latest government exam results, merit lists and result updates on Sarkari Resultess.

Answer & Explanation

4 Answers

Verified Correct Answer

Option A

SELECT id,COALESCE(city,'Unknown') AS city FROM customers;

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 column = NULL.

Additional Explanation

This option is incorrect for the stated requirement.

Verified

Option C

Use NOT IN without considering NULLs in the subquery.

Additional Explanation

This option is incorrect for the stated requirement.

Verified

Option D

Use COUNT(column) when you need to count NULL values too.

Additional Explanation

This option is incorrect for the stated requirement.