What is database normalization and what does third normal form (3NF) require?

• A. Normalization reduces redundancy, but 3NF allows some transitive dependencies.
• B. 3NF requires a completely flat schema without any relations.
• C. Normalization reduces redundancy; 3NF requires no transitive dependencies.
• D. 3NF is mainly about performance tuning and indexing.

Answer: (C)

Normalization organizes data so that it minimizes redundancy and keeps data integrity by splitting information into related tables and defining clear dependencies. Third normal form builds on this by removing transitive dependencies, meaning every non-key attribute should depend directly on a key rather than through another non-key attribute.

A transitive dependency occurs when a non-key attribute depends on another non-key attribute that itself depends on the key. In 3NF, that kind of chain is not allowed. To illustrate, if you have a table with a primary key like StudentID, and you store DepartmentID and DepartmentName in the same table, DepartmentName depends on DepartmentID, which isn’t the key. That’s a transitive dependency. Decomposing into a separate Department table (DepartmentID, DepartmentName) ensures DepartmentName depends only on the Department’s key, while the Student table remains focused on student data.

So the essence is: normalization reduces redundancy, and 3NF requires no transitive dependencies, with non-key attributes depending directly on a key. The other statements aren’t accurate because 3NF is not about keeping a flat, single table, nor about performance tuning and indexing.