1560. Top customer by revenue — Banking — implementation variant 10

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

In a Banking application, implement this production problem: Find the customer with the highest completed revenue. 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

SELECT * 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 B

SELECT customer_id,SUM(total_amount) revenue FROM orders WHERE status='completed' GROUP BY customer_id ORDER BY revenue DESC LIMIT 1;

Additional Explanation

Aggregate first, then order by the aggregate. Add a deterministic tie-breaker when required.

Verified

Option C

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 D

DELETE FROM the_table;

Additional Explanation

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