| 嵌套关系数据模型中的自然连接运算 |
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| 引用本文： | 左万利.嵌套关系数据模型中的自然连接运算[J].吉林大学学报(理学版),1996(4). |
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| 作者姓名： | 左万利 |
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| 作者单位： | 吉林大学计算机科学系 |
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| 摘 要： | 从关系和子关系的观点出发，探讨了非一阶关系数据库中自然连接操作的语义问题．通过引入连接路径，扩展并重新定义了嵌套关系数据模型中的自然连接运算，使其可以直接作用于关系局部．同时证明了ＰＮＦ关系对于扩展后的自然连接运算的封闭性．
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| 关 键 词： | 非一阶关系，嵌套关系，自然连接，PNF关系 |
On the Natural Join Operation of the Nested Relational Data Model |
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| Zuo Wanli.On the Natural Join Operation of the Nested Relational Data Model[J].Journal of Jilin University: Sci Ed,1996(4). |
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| Authors: | Zuo Wanli |
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| Abstract: | Starting from the concept of relation and sub-ralation, this paper deals with the semantics of natural join operation for the non--first--normal-form relational databases. By introducing join--path,a more generalized natural join definition for the nested relational data model is presented, which can act both on relations and sub--relations directly. It is also proved that PNF relations are closed under the further extended natural join operation. |
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| Keywords: | NINF relation nested relation natural join PNF relation |
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