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Code reviewHardcr-g202
Subject Phantom readLevel Senior–Staff~30 minCommon in Databases & SQL interviewsIndustries Software development

Question

Review this Python booking function meant to prevent double-booking a room.

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
def book_room(conn, room_id, start, end):    conn.set_isolation_level(REPEATABLE_READ)    cur = conn.cursor()    cur.execute(        "SELECT count(*) FROM bookings "        "WHERE room_id = %s AND tsrange(start, stop) && tsrange(%s, %s)",        (room_id, start, end))    if cur.fetchone()[0] == 0:        cur.execute(            "INSERT INTO bookings (room_id, start, stop) VALUES (%s,%s,%s)",            (room_id, start, end))    conn.commit()
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