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 that can occur in a database.
To achieve 4NF, a table must first satisfy the requirements of 3NF. Additionally, it must not have any multi-valued dependencies. A multi-valued dependency occurs when a non-key attribute is functionally dependent on only a part of the primary key.
To eliminate multi-valued dependencies and achieve 4NF, the table can be split into two or more separate tables. Each table will have its own primary key and will be related to the others through foreign keys. This process is known as decomposition.
By decomposing the table, redundancy and data anomalies can be minimized. It allows for more efficient storage and retrieval of data, as well as better data integrity and consistency.
In summary, the fourth normal form (4NF) in database normalization is a level of normalization that eliminates multi-valued dependencies by decomposing a table into multiple tables. This helps to improve data integrity and reduce redundancy in the database.