Data Analysis for Database Design
Normalization Example
- Third Normal Form:
- Entities are assumed to be in 2NF before beginning 3NF analysis.
- Third normal form analysis looks for two types of problems, derived data and transitive dependencies.
- In both cases, the fundamental error is that non key attributes are dependent on other non key attributes.
- Derived attributes are those whose values can either be calculated from other attributes, or derived through logic from the values of other attributes.
- A transitive dependency exists when a non-key attribute is dependent on another non-key attribute (other than by derivation).
- Transitive analysis is only performed on those entities that do not have a concatenated key.