Database Design for Mere Mortals™: A Hands-On Guide to Relational Database Design, Second Edition

Dependencies: The Good, the Bad, and the Ugly

The notion of dependencies (and modification anomalies, for that matter) falls under the umbrella of Dependency Theory. Dependency Theoryis the field of study comprising Normalization Theory, dependency principles, and other related topics. You learned earlier that most Normal Forms are based on various types of dependencies, and it is for this reason that you must study them. Once you understand dependencies in general, Normal Forms are much easier to learn and understand.

Note

This is by no means an exhaustive study of dependencies. The idea here is to provide you with a solid idea of what dependencies are about and how they fit into Normalization.

There are four types of dependencies we'll ...