Elementary key normal form
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Elementary key normal form (EKNF) is a subtle enhancement on third normal form, thus EKNF tables are in 3NF by definition. This happens when there is more than one unique composite key and they overlap. Such cases can cause redundant information in the overlapping column(s).
A table is in EKNF, if and only if, all its elementary functional dependencies begin at whole keys or end at elementary key attributes.
For every full non-trivial functional dependency of the form X→Y, either X is a key or Y is (a part of) an elementary key.
Example
See also
- Database Normalization
- First Normal Form
- Second Normal Form
- Third Normal Form
- Boyce–Codd Normal Form
- Canonical form
Notes and references
- Joe Celko’s SQL for Smarties: Advanced SQL Programming, Third Edition
- A New Normal Form for the Design of Relational Database Schemata by CARLO ZANIOLO - Sperry Research Center[1]
- Information Modeling and Relational Databases By T. A. Halpin, Antony J. Morgan, Tony Morgan