Mw. Vincent et B. Srinivasan, INSERTION ANOMALIES AND THE JUSTIFICATION FOR 4NF IN RELATIONAL DATABASES, Information sciences, 81(1-2), 1994, pp. 87-102
Citations number
34
Categorie Soggetti
Information Science & Library Science","Computer Science Information Systems
The issue of providing a formal justification for the use of fourth no
rmal form (4NF) in relational database design is investigated. Extendi
ng earlier work by other authors that provided formal definitions of a
n insertion anomaly in the case of functional dependency (FD) constrai
nts, formal definitions are provided for two types of an insertion ano
maly for the case when both FD and multivalued dependency (MVD) constr
aints are permitted. It is shown that both types of insertion anomaly
are equivalent conditions on a relation scheme and a relation scheme i
s in 4NF if and only if both anomalies are absent. It is also shown th
at another type of insertion anomaly that does not reflect the symmetr
ical nature of MVDs is a weaker condition than 4NF.