| 摘要: |
| 将面向对象模型与面向值的模型相结合，可兼得二者的优点．本文基于具有组合元组标识的ＮＦ2关系模型给出了强调嵌套结构特征的关系运算投影IIs和自然连接，并在此基础上研究ＮＦ2关系数据模型中的类、子类及其间的属性继承的语义及形式化定义；引入了Ｓ－子类的概念；研究了公共子类及多属性继承的特征．所有的讨论基于组合元组标识，具有较强的面向对象模型的特征． |
| 关键词: NF2关系模型，关系运算，类．子类，属性继承 |
| DOI： |
| 分类号: |
| 基金项目:本课题由国家自然科学基金和河北省自然科学基金资助. |
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| THE ATTRIBUTE INHERITANCE IN NF2 RELATIONAL MODEL |
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Li Tianzhu
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| Abstract: |
| Combining object oriented model with value-based model would help getting the merits of both models. In this paper, based on NF2 relational model with composited tuple identity, the operations of projection if and natural join keeping the nested structure of relations, are given. From this, the authors have studied the semantics and formallied definition for class, subclass, attribute inheritance in NF2 relational model, introducing a special attribute R" and concept of S-subclass, discussed the common sub class and multiple inheritance. All of the discussions are based on composited tuple identity, possessing the features in O-O model. |
| Key words: NF2 relational model, relational operation, class, subclass, inheritance. |
