Normalise relations to third normal form
Additional Information
Students should know what properties are possessed by a relation in third normal form.
Database normalisation is the process of organising database columns and tables to reduce data redundancy and improve data integrity.
- Eliminates redundant data (removes duplicates)
- Reducing inconsistencies (i.e. Carl = Karl)
- Data is coherent
- A process of elimination
- To remove data into smaller groups
There are 3 stages of Database Normalisation. There is also the Unnormalised form.
- 1st Normal Form - Removes all repeating groups - i.e. customer details split into customer table
- 2nd Normal Form - Remove all partial dependenices (breaking many to many)
- 3rd Normal Form - Removes all non-key dependencies (using foreign keys)
- Data is atomic
- No repeating groups
- No partial dependencies
- No non-key dependencies
Understand why databases are normalised
Databases are normalised to:
- Reduce data redundancy
- Improve data integrity
- Reduces duplicated data
- Reduces Redundancy
- Increases consistency and integrity
- Easier to maintain