フリー問題

問題文

An analyst reports that the average order value for a region is higher than expected. Investigation shows that a quarter of the rows have a null discount_amount, and the reported figure uses AVG on that column. What does the null handling mean for the figure?

選択肢

1. The nulls are treated as zero, which lowers the average for the whole region and for the quarter because the divisor still counts every row.
2. The average returns null for the whole region and for the quarter because any null in the input propagates to the aggregate result.
3. The average is computed over the rows that hold a value, so the rows with nulls are excluded from both the sum and the divisor.
4. The average is computed twice, once including and once excluding nulls, and the larger of the two is returned, and the choice is not configurable.