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| Database Normalization |
Databases are either unnormalized, or normalized according to five levels of rules.
- First Normal Form
- Eliminate repeating groups in individual tables.
- Create a separate table for each set of related data.
- Identify each set of related data with a primary key.
- Second Normal Form
- Create separate tables for sets of values that apply to multiple records.
- Relate these tables with a foreign key.
- Third Normal Form
- Eliminate fields that do not depend on the key.
- Fourth Normal Form
- In a many-to-many relationship, do not store independent entities in the same table.
- Fifth Normal Form
- You must be able to reconstsruct the original table from the tables into which it has been broken down.
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