【2019年8月版本】OCP 071认证考试最新版本的考试原题-第4题

choose two

Exammine the desciption of the PRODUCT DETALS table:

NAME  NULL  TYPE

--------------------------------------------------

PRODUCT_ID  NOT NULL  NUMBER(2)

PRODUCT_NAME  NOT NULL  VARCHAR2(25)

PRODUCT_PRICE  NUMBER(8,2)

EXPIRY_DATE  DATE

Which two statements are true?

A) PRODUCT_ID can be assigned the PEIMARY KEY constraint.

B) EXPIRY_DATE cannot be used in arithmetic expressions.

C) EXPIRY_DATE contains the SYSDATE by defalt if no date is assigned to it

D) PRODUCT_PRICE can be used in an arithmetic expression even if it has no value stored in it

E) PRODUCT_PRICE contains the value zero by default if no value is assigned to it.

F) PRODUCT_NAME cannot contain dupicate values.

Answer：AD

(解析：A 答案考的是如果有非空约束还能不能再添加主键约束，答案是可以。number 型的列即使是空值也可以出现在数学表达式上，但是最后的结果会是空值。)