Question Discussion & Solution

🔑 Key Points

• A table is in Third Normal Form (3NF) if it meets the criteria for Second Normal Form (2NF) and has no transitive dependencies.
• Specifically, there must be no transitive dependency of a non-prime attribute on a candidate key.
• This means that no non-prime attribute should be functionally dependent on another non-prime attribute which, in turn, is dependent on the candidate key.
• The goal of 3NF is to eliminate redundancy caused by transitive dependencies, ensuring all non-key attributes are directly dependent on the primary key.

📄 Additional Information

• A transitive dependency essentially means there is an indirect dependency: \( A \rightarrow B \) and \( B \rightarrow C \), therefore \( A \rightarrow C \). In 3NF, if A is the candidate key, then B should not be a non-prime attribute (or if it is, C must be part of B).
• To resolve 3NF violations, the transitively dependent attributes are moved to a new table, with the intermediate attribute becoming the primary key of the new table and a foreign key in the original table.
• This further reduces update anomalies and maintains data consistency.