フリー問題

問題文

A sum over an order table joined to a shipment table returns twice the expected amount. What explains that?

選択肢

1. The join multiplies the column types before the summation, and the fix aggregates the sorted labels on each side separately.
2. The join multiplies the column types before the summation, and the fix aggregates the measured amounts on each side separately.
3. The join multiplies the matching rows before the summation, and the fix aggregates the measured amounts on each side separately.
4. The join multiplies the matching rows before the summation, and the fix aggregates the sorted labels on each side separately.