单选题
Which of the following statements about object oriented database is NOT correct ?
A、
Each object has a unique object identity in the system
B、
Encapsulation and inheritance are two important features of object oriented database
C、
A subclass can inherit the attributes and methods of all its superclasses
D、
A superclass includes the attributes and methods of all its subclasses
【正确答案】
D
【答案解析】
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