Database Normalization

Following is a brief summary of some of the concepts and terms used to describe and define database normalization:

First Normal Form (1NF)

Second Normal Form (2NF)

Third Normal Form (3NF)


Remember that in the "real world", that practical concerns about convenience and performance will override some of the theoretical notions of normalization! So a design that includes some controlled data duplication to speed up performance (such as storing postal and zip codes, which could otherwise be looked up against the information in the street, city, and state or province of an address; or a design that includes 1:1 relationships to segregate unwieldy data types such as large images or moving images, will be preferred over a design that strictly goes "by the rules". This is part of the art of database design: where theory and practice meet.