Functional Dependency and Other Related Dependencies

Abstract

The invention and rise of the relational database starting in the 1960s was accompanied by the remarkable development of canonical design techniques, making it possible to avoid many database designs with unintended bad consequences (Codd, 1970, 1971). These techniques, called “normal forms,” prevent the occurrence of what are called “anomalies.” If a database design contains an anomaly, the implemented database will behave in unintended ways. If there is a deletion anomaly, data will unexpectedly disappear; an insertion anomaly will produce difficulties in adding data; and a modification anomaly will result in extra and unexpected operations in the course of changing data in the database (Kroenke, 2002).