Please use this identifier to cite or link to this item: https://doi.org/10.1007/BF01976278
Title: NF-NR: A practical normal form for nested relations
Authors: Ling, T.-W. 
Yan, L.-L. 
Keywords: Entity-Relationship Approach
extended-functional dependency
Nested relation
normal forms
Issue Date: Dec-1994
Source: Ling, T.-W.,Yan, L.-L. (1994-12). NF-NR: A practical normal form for nested relations. Journal of Systems Integration 4 (4) : 309-340. ScholarBank@NUS Repository. https://doi.org/10.1007/BF01976278
Abstract: We propose a normal form for nested relations, called NF-NR, which removes undesirable anomalies from a nested relational database schema. Both functional dependencies and multivalued dependencies are considered. NF-NR reduces to 3NF/4NF if the nested relation considered is actually a flat relation. Especially, NF-NR removes global redundancies among a set of nested relations. Two approaches to NF-NR database design, namely the restructuring rules approach and the ER approach, are discussed. We relate NF-NR to ER-NF, a normal form of ER defined earlier, by defining a simple mapping from an ERD in ER-NF to a set of nested relations in NF-NR. This approach effectively removes ambiguitics and redundancies on a semantic level and hence gives a set of nested relations with clean semantics and yet in good normal form. A set of desirable properties for any normal form for nested relations are described and an evaluation of several existing normal forms is given based on this set of properties. The evaluation shows that NF-NR improves over previously proposed normal forms in various aspects and is a more practical normal form for nested relations. © 1994 Kluwer Academic Publishers.
Source Title: Journal of Systems Integration
URI: http://scholarbank.nus.edu.sg/handle/10635/111194
ISSN: 09254676
DOI: 10.1007/BF01976278
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