Normalisationis a process which we
analyze and alter a database relation in order to get more concise and
organized data structures. Normalised data is stable and has a natural
structure. We call a relation normalized if:
- it does not contain any redundancy
- it does not cause maintenance problems
- it is an accurate representation of the data
Relations that aren't normalised contain non-atomic attributes and
therefore can contain redundant information. Detailed planning of the ERM can
help creating normalised relations. The following steps will explain how
existing relations can be normalised step by step.