normal form : Java Glossary
©1996-2017 Roedy Green of Canadian Mind Products
- normal form
In SQL (Standard Query Language), there are five rules of sensible database design
called the five normal forms. Briefly they are:
- No repeating groups of data within a row. Instead of having an Author1, Author2
and Author3 field, you should put the Author information in a separate table.
- Every non-key item must depend on the entire primary key. Don’t replicate
data that depends only on part of the key.
- Each non-key item must be a fact about the primary key item, not some other
- Don’t mix two different one to many relationships in the same table.
- Break tables up as small as possible so that each fact is recorded in only one
place in the database. In practice, you have to balance this general rule against
the extra overhead of many small tables.