On keys and normal forms

In this paper, we give a necessary and sufficient condition for a Boyce-Codd Normal Form (BCNF) relation scheme to be in Fourth Normal Form (4NF). We also give a necessary and sufficient condition for a 4NF relation scheme to be in Projection-Join Normal Form (PJNF). From these results, we derive ne...

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Veröffentlicht in:	Information processing letters 1997-06, Vol.62 (5), p.255-258
1. Verfasser:	Mok, Wai Yin
Format:	Artikel
Sprache:	eng
Schlagworte:	Algorithmics. Computability. Computer arithmetics Applied sciences Boyce-Codd Normal Form Computer science control theory systems Exact sciences and technology Fourth Normal Form Information processing Normalization Projection-Join Normal Form Relational data bases Relational databases Studies Theoretical computing Third Normal Form
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Zusammenfassung:	In this paper, we give a necessary and sufficient condition for a Boyce-Codd Normal Form (BCNF) relation scheme to be in Fourth Normal Form (4NF). We also give a necessary and sufficient condition for a 4NF relation scheme to be in Projection-Join Normal Form (PJNF). From these results, we derive necessary and sufficient conditions for a BCNF relation scheme to be in PJNF. In addition, we give a less stringent condition for a Third Normal Form (3NF) relation scheme to be in BCNF. Finally, we show that our theorems generalize the results by Date and Fagin (1992).
ISSN:	0020-0190 1872-6119
DOI:	10.1016/S0020-0190(97)00076-8