フリー問題

問題文

A specialist needs the rows sorted by order date descending and then by customer ascending, using the DataFrame API. Which approach expresses both directions?

選択肢

1. Call sort on the date and then use limit, because limit preserves the secondary ordering of the underlying table.
2. Call sort with two column expressions, applying the descending helper to the date column and leaving the other ascending.
3. Call sort with the two column names as strings and pass a single direction flag, which applies to both columns.
4. Call sort twice, first on customer and then on the date, because the last call decides the primary key of the ordering.