3105. Reporting: Find customers contributing to 80% cumulative revenue. — Production Debugging

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

In a reporting module, solve this as a production problem using Production Debugging: Find customers contributing to 80% cumulative revenue. 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.

Verified Correct Answer

Option B

WITH x AS (SELECT customer_id,SUM(total_amount) revenue FROM orders WHERE status='completed' GROUP BY customer_id), r AS (SELECT x.*,SUM(revenue) OVER(ORDER BY revenue DESC,customer_id) cumulative,SUM(revenue) OVER() total FROM x) SELECT *,100*cumulative/total cumulative_pct FROM r WHERE cumulative-revenue<0.8*total;

Additional Explanation

The cumulative window calculation identifies the Pareto-style revenue cutoff.

Verified

Option C

SELECT * FROM table_name;

Additional Explanation

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

Verified

Option D

DELETE FROM table_name;

Additional Explanation

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