数据库关系中对空值的功能依赖和约束

Q4 Mathematics
Paolo Atzeni, Nicola M. Morfuni
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引用次数: 105

摘要

考虑了信息不完全的数据库关系。采用空值的无信息解释,具有通用性和自然性的特点。与框架及其动机相一致,研究了两类有意义的完整性约束:(a)在经典关系理论中得到广泛研究的功能依赖;(b)空值约束,控制关系中null的存在。具体来说,考虑了空值的三种约束类型(无空子方案、存在性约束、析取存在性约束),并研究了它们与函数依赖的相互作用。在这三种情况下,分别解决了推理问题,分析了其求解算法的复杂性,并讨论了完全公理化的存在性。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Functional dependencies and constraints on null values in database relations

Database relations with incomplete information are considered. The no-information interpretation of null values is adopted, due to its characteristics of generality and naturalness. Coherently with the framework and its motivation, two meaningful classes of integrity constraints are studied: (a) functional dependencies, which have been widely investigated in the classical relational theory and (b) constraints on null values, which control the presence of nulls in the relations. Specifically, three types of constraints on null values are taken into account (nullfree subschemes, existence constraints, disjunctive existence constraints), and the interaction of each of them with functional dependencies is studied. In each of the three cases, the inference problem is solved, the complexity of the algorithms for its solution analyzed, and the existence of a complete axiomatization discussed.

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来源期刊
信息与控制
信息与控制 Mathematics-Control and Optimization
CiteScore
1.50
自引率
0.00%
发文量
4623
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