Code reviewHardcr-g200

Subject DeadlockLevel Senior–Staff~30 minCommon in Databases & SQL · Concurrency interviewsIndustries Software development

Question

Review this Python (psycopg2) money-transfer function.

What a strong answer looks like

Separate real bugs from style. Rank issues by severity, point at the root cause rather than the symptom, and suggest a concrete fix — specific and kind.

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Code to reviewpython

1def transfer(conn, src, dst, amt):2    with conn:  # transaction3        cur = conn.cursor()4        cur.execute(5            "UPDATE accounts SET balance = balance - %s WHERE id = %s",6            (amt, src))7        cur.execute(8            "UPDATE accounts SET balance = balance + %s WHERE id = %s",9            (amt, dst))

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