Normalisation is one of the most important — and most misunderstood — topics in IB Computer Science databases. Many students memorise definitions of normal forms without understanding why normalisation exists or what problem it solves.
In IB exams, students are not expected to memorise advanced theory. They are expected to explain the purpose of normalisation, how it improves database design, and what problems occur without it.
What Is Normalisation?
Normalisation is the process of organising data in a database to:
- Reduce data duplication
- Improve data consistency
- Prevent update errors
It involves:
- Splitting data into multiple related tables
- Linking tables using primary and foreign keys
The goal is to ensure that each piece of data is stored once, in the most appropriate place.
Why Normalisation Is Needed
Without normalisation, databases suffer from anomalies.
These include:
- Update anomalies – changing data in one place but not another
- Insertion anomalies – being unable to add data without unrelated information
- Deletion anomalies – losing important data when records are removed
Normalisation eliminates these problems by enforcing logical structure.
First Normal Form (1NF)
In First Normal Form (1NF):
