OCP-1Z0-051-2015-54題
阿新 • • 發佈:2019-01-06
QUESTION NO: 54
Which statements are correct regarding indexes? (Choose all that apply.)
A. For each data manipulation language (DML) operation performed, the corresponding indexes
are automatically updated.
B. A nondeferrable PRIMARY KEY or UNIQUE KEY constraint in a table automatically creates a
unique index.
C. A FOREIGN KEY constraint on a column in a table automatically creates a non unique key
D. When a table is dropped, the corresponding indexes are automatically dropped
Answer: A,B,D
A正確,在具有索引的表上提交每項DML 操作後,都意味著必須更新相應的索引。
B正確,在表定義中定義了PRIMARY KEY 或UNIQUE 約束條件,則會自動建立一個唯一的索引。
C錯誤,外來鍵不能夠自動建立索引,只有主鍵約束和唯一性約束才能自動建立唯一的索引。
D正確,在刪除表時,會刪除相應的索引。
Which statements are correct regarding indexes? (Choose all that apply.)
A. For each data manipulation language (DML) operation performed, the corresponding indexes
are automatically updated.
B. A nondeferrable PRIMARY KEY or UNIQUE KEY constraint in a table automatically creates a
unique index.
C. A FOREIGN KEY constraint on a column in a table automatically creates a non unique key
D. When a table is dropped, the corresponding indexes are automatically dropped
Answer: A,B,D
Explanation:
D正確,在刪除表時,會刪除相應的索引。