Normalisation of a table

Question

Ask a quite stupid question here...

Based on http://www.sqa.org.uk/e-learning/MDBS01CD/page_30.htm#Non

It said that "Take each non-key attribute in turn and ask the question: is this attribute dependent on one part of the key?(paragraph 5)"

Actually how do I know whether a non-key attribute is dependent on a composite key or it depends on a part of the composite key only?

Could you all provide an explanation?Thanks!

Answer 1

You need to know what business rules your database design is supposed to satisfy. The aim of normalization is to help ensure that the business rules (i.e. the set of dependencies you wish to implement) are properly supported by the keys and other integrity constraints in your data model.

Write down the set of functional dependencies before you start and use that as the basis of your normalization exercise.