試題詳解

18 擬從一產品（Product）資料表，查詢產品編號（P_code），並且按產品編號由大至小順序排序，相同之 產品編號不重複列出。下列何者為最適合之結構化查詢語言？
(A)SELECT P_code FROM Product ORDER BY P_code ASC
(B)SELECT P_code FROM Product ORDER BY P_code DESC
(C)SELECT DISTINCT P_code FROM Product ORDER BY P_code ASC
(D)SELECT DISTINCT P_code FROM Product ORDER BY P_code DESC