2349. Data migration: Migrate active customers into an archive table without duplicates. — Python + FastAPI + SQLAlchemy

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

In a data migration module, solve this as a production problem using Python + FastAPI + SQLAlchemy: Migrate active customers into an archive table without duplicates. 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

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 B

INSERT INTO customer_archive (id,name,email,city,created_at) SELECT c.id,c.name,c.email,c.city,c.created_at FROM customers c LEFT JOIN customer_archive a ON a.id=c.id WHERE c.status='active' AND a.id IS NULL;

Additional Explanation

The LEFT JOIN prevents inserting IDs already present in the archive. A unique key on archive.id is still required.

Verified

Option C

DELETE FROM table_name;

Additional Explanation

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

Verified

Option D

UPDATE table_name SET status='active';

Additional Explanation

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