【2019年8月版】OCP 071認證考試原題-第36題

Choose three

Which three statements are true about sequences in a single instance Orade database?

A) A sequence's unallocated cached values are lost if the instance shuts down.

B) Two or more tables cannot have keys generated from the same sequence.

C) A sequence number that was allocated can be rolled back if a transaction fails.

D) A sequence can issue duplicate values.

E) Sequences can always have gaps.

F) A sequence can only be dropped by a DBA.

Answer：：ADE

(解析：虛擬能夠一會兒產生一組的數字緩存在內存中，可是實例關閉，沒有用到的數字也將丟失;序列能夠產生重複的值在定義的時候用 cycle 關鍵字，步長若是不是定義爲 1，則產生的數字就不是連續的。)