OOP技术由对象、消息、方法、类和继承五个方面组成。

OOP consists of five aspects: object, message, method, class and inheritance.

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继承：标注——单个表、联合表和按类表。

Inheritance: Annotations — Single table, joined table, and table per class.

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继承：标注——单个表、联合表和按类表。

Inheritance: Annotations — Single table, joined table, and table per class.

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