The highest normal form of relational schema R is the fifth normal form(5NF) if all candidate keys in its functional dependency set are the determining factors.
The fifth normal form means that, in a relational pattern R, R conforms to the fifth normal form if all of its non-trivial multivalued dependencies are contained by its candidate keys.
Because the candidate keys contain all the functional dependencies, this means that there is no redundant data in this relational pattern, nor is there any case of abnormal data update, so this relational pattern conforms to the highest normal form, the fifth normal form.
