Data modelling - Process
Normalisation
Organising a database so each fact is stored cleanly with minimal unnecessary duplication
What's it for?
Reduces duplicate data so updates stay consistent and easier to trust.
For example…
Customer addresses live in one table and orders reference them, instead of copying the address onto every order row.
Instead of storing a customer's address on every order, a normalised database stores the customer once and links orders back to that record
Think of it like…
Keeping one master contact card and pointing to it, rather than photocopying the card into every filing folder
Often confused with…
- DenormalisationDeliberately duplicating some data to make reading or reporting faster and simpler
- 1NF (First Normal Form)A database rule that says each field should hold one value, not a list of values
- 2NF (Second Normal Form)A database rule that moves information out when it depends on only part of a combined key
- 3NF (Third Normal Form)A database rule where non-key information depends directly on the record's key