1474. Previous order comparison — Real Estate — implementation variant 24

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

In a Real Estate application, implement this production problem: Show each customer's previous order amount. 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.

Looking for the latest Sarkari Result 2026 updates? Check the latest government exam results, merit lists and result updates on Sarkari Resultess.

Answer & Explanation

4 Answers

Verified

Option A

DELETE FROM the_table;

Additional Explanation

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

Verified

Option B

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 C

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 D

SELECT id,customer_id,order_date,total_amount,LAG(total_amount) OVER(PARTITION BY customer_id ORDER BY order_date,id) previous_amount FROM orders;

Additional Explanation

LAG reads the previous row inside each customer's chronological partition.