2373. Customers: Find customers whose spending increased month-over-month. — Python + FastAPI + SQLAlchemy

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

In a customers module, solve this as a production problem using Python + FastAPI + SQLAlchemy: Find customers whose spending increased month-over-month. 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

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

WITH m AS (SELECT customer_id,DATE_FORMAT(order_date,'%Y-%m') month,SUM(total_amount) revenue FROM orders WHERE status='completed' GROUP BY customer_id,DATE_FORMAT(order_date,'%Y-%m')) SELECT *,revenue-LAG(revenue) OVER(PARTITION BY customer_id ORDER BY month) change_amount FROM m;

Additional Explanation

LAG compares each month's revenue with the previous available month.

Verified

Option D

DELETE FROM table_name;

Additional Explanation

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