2352. Migration validation: Compare row counts between two tables. — Python + FastAPI + SQLAlchemy

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

In a migration validation module, solve this as a production problem using Python + FastAPI + SQLAlchemy: Compare row counts between two tables. 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 (SELECT COUNT(*) FROM source_table) source_count,(SELECT COUNT(*) FROM target_table) target_count;

Additional Explanation

Counts are a first validation step; key-level and checksum-level comparisons are needed for stronger validation.

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.