フリー問題

問題文

By mistake the same set of lines is fed in twice on one day. A member worries that the hub now holds two of everything for each buyer. What actually happens on the second attempt?

選択肢

1. Reloading the same row updates the surviving record which the nominated key points to at once.
2. Reloading the same row updates the distinct record which the clocked key points to at once.
3. Reloading the same row updates the surviving record which the clocked key points to at once.
4. Reloading the same row updates the distinct record which the nominated key points to at once.