問題詳情
49. 設計一個關聯式資料表(Relational Tables) Customer (cid, name, dep_name, balance)，分別表示客戶編號、客戶姓名、客戶任職單位、餘額，假設要列出不屬於任何單位客戶姓名，其條件寫法為以下何者？
(A) dep_name = {}
(B)dep_name = NULL
(C) dep_name IS NULL
(D)dep_nameAS EMPTY。
(A) dep_name = {}
(B)dep_name = NULL
(C) dep_name IS NULL
(D)dep_nameAS EMPTY。
參考答案
答案：C
難度：計算中-1
書單：沒有書單，新增
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