フリー問題

問題文

A design tries to build the row identifier over the result of an expression, and the server turns that request down. What does the identifier need that the invisible helper cannot give?

選択肢

1. The identifier needs a numbered placeholder for every row of that representation.
2. The identifier needs a temporary placeholder for every row of that representation.
3. The identifier needs a hidden placeholder for every row of that representation.
4. The identifier needs a materialized placeholder for every row of that representation.