3716. Performance: Avoid N+1 by fetching orders and customers in one query. — Data Migration

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

In a performance module, solve this as a production problem using Data Migration: Avoid N+1 by fetching orders and customers in one query. Provide the SQL, explain the logic, show safe application integration, and mention failure/edge cases.

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Answer & Explanation

4 Answers

Verified

Option A

UPDATE table_name SET status='active';

Additional Explanation

Incorrect: it does not satisfy the stated business rule and can return/change unintended data.

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Option B

SELECT * FROM table_name;

Additional Explanation

Incorrect: it does not satisfy the stated business rule and can return/change unintended data.

Verified Correct Answer

Option C

SELECT o.id,o.total_amount,c.id customer_id,c.name customer_name FROM orders o JOIN customers c ON c.id=o.customer_id WHERE o.status='completed' LIMIT 100;

Additional Explanation

A join can replace one query per order when the related data is required together.

Verified

Option D

DELETE FROM table_name;

Additional Explanation

Incorrect: it does not satisfy the stated business rule and can return/change unintended data.