2358. Data quality: Find orders referencing missing customers. — Python + FastAPI + SQLAlchemy

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

In a data quality module, solve this as a production problem using Python + FastAPI + SQLAlchemy: Find orders referencing missing customers. Provide the SQL, explain the logic, show safe application integration, and mention failure/edge cases.

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Answer & Explanation

4 Answers

Verified Correct Answer

Option A

SELECT o.id,o.customer_id FROM orders o LEFT JOIN customers c ON c.id=o.customer_id WHERE c.id IS NULL;

Additional Explanation

Foreign keys should prevent new orphan orders; this query detects legacy corruption.

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

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.

Verified

Option D

DELETE FROM table_name;

Additional Explanation

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