フリー問題

問題文

A query calls SUBSTR on a telephone column with a starting position of minus four and a length of four. The column holds values of differing lengths. Which characters does the call return?

選択肢

1. The count is rejected and the call returns a null for each row that the query reads.
2. The count is treated as one and the call returns the first four characters in the column.
3. The count runs backward from the end of the value and the call returns everything ahead of the final four characters.
4. The count runs backward from the end of the value and the call returns the final four characters.