3938. Customers: Find the top customer by completed revenue in each city. — Architecture

DBMS Published Updated 0 Views Verified
In a customers module, solve this as a production problem using Architecture: Find the top customer by completed revenue in each city. Provide the SQL, explain the logic, show safe application integration, and mention failure/edge cases.
Looking for the latest Sarkari Result 2026 updates? Check the latest government exam results, merit lists and result updates on Sarkari Resultess.
Sarkari Resultess
Questions & Answers

Answer & Explanation

4 Answers
Verified

Option A

SELECT * FROM table_name;
Additional Explanation
Incorrect: it does not satisfy the stated business rule and can return/change unintended data.
Sarkari Resultess
Editorial Answer 1
Verified

Option B

DELETE FROM table_name;
Additional Explanation
Incorrect: it does not satisfy the stated business rule and can return/change unintended data.
Sarkari Resultess
Editorial Answer 2
Verified

Option C

UPDATE table_name SET status='active';
Additional Explanation
Incorrect: it does not satisfy the stated business rule and can return/change unintended data.
Sarkari Resultess
Editorial Answer 3
Verified Correct Answer

Option D

WITH totals AS (SELECT c.city,c.id,c.name,SUM(o.total_amount) revenue FROM customers c JOIN orders o ON o.customer_id=c.id AND o.status='completed' GROUP BY c.city,c.id,c.name) SELECT * FROM (SELECT totals.*,ROW_NUMBER() OVER(PARTITION BY city ORDER BY revenue DESC,id) rn FROM totals) x WHERE rn=1;
Additional Explanation
Aggregate revenue first, then rank within each city.
Sarkari Resultess
Editorial Answer 4