Database Normalisation Questions
The third normal form (3NF) is a level of database normalization that builds upon the first and second normal forms. In 3NF, a table is considered to be in third normal form if it meets the following criteria:
1. It is already in second normal form (2NF).
2. All non-key attributes (attributes that are not part of the primary key) are dependent only on the primary key.
3. There are no transitive dependencies between non-key attributes.
To explain further, in 3NF, every non-key attribute must depend directly on the primary key and not on any other non-key attribute. Additionally, there should be no indirect dependencies between non-key attributes. This means that if attribute A depends on attribute B, and attribute B depends on attribute C, then attribute A should not depend on attribute C.
By achieving 3NF, a database table is more optimized, reduces data redundancy, and ensures data integrity by eliminating unnecessary dependencies.