Database Normalisation Questions
The fourth normal form (4NF) in database normalization is a level of database normalization that builds upon the third normal form (3NF). It aims to eliminate certain types of data anomalies known as multi-valued dependencies.
In 4NF, a relation is considered to be in this form if it is already in 3NF and does not have any non-trivial multi-valued dependencies. A non-trivial multi-valued dependency occurs when a relation has at least three attributes, A, B, and C, where A determines B and C, and B and C are independent of each other.
To achieve 4NF, the relation needs to be decomposed into multiple relations, each containing a subset of the original attributes. This decomposition helps in eliminating the multi-valued dependencies and ensures that the data is stored efficiently and without redundancy.
Overall, the fourth normal form helps in further reducing data redundancy and improving data integrity in a database.