1265. Duplicate email detection — Sarkari Result — implementation variant 15

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

In a Sarkari Result application, implement this production problem: Find duplicate non-null customer email addresses. The API/service receives user input and must return or modify data safely. Give the SQL solution, explain why it works, and show how the same operation is called from the selected stack.

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Answer & Explanation

4 Answers

Verified

Option A

UPDATE the_table SET status='active';

Additional Explanation

Incorrect: it does not implement the stated business rule and may modify/fetch the wrong rows.

Verified

Option B

SELECT * FROM the_table;

Additional Explanation

Incorrect: it does not implement the stated business rule and may modify/fetch the wrong rows.

Verified

Option C

DELETE FROM the_table;

Additional Explanation

Incorrect: it does not implement the stated business rule and may modify/fetch the wrong rows.

Verified Correct Answer

Option D

SELECT email,COUNT(*) cnt FROM customers WHERE email IS NOT NULL GROUP BY email HAVING COUNT(*)>1;

Additional Explanation

GROUP BY forms duplicate groups and HAVING filters groups after aggregation.