Which of the following statements about Third Normal Form (3NF) is true?

Correct option is A

A table is said to be in Third Normal Form (3NF) if:
1. It is in Second Normal Form (2NF).
2. Every non-prime attribute (attributes not part of any candidate key) is directly dependent on the primary key and is not transitively dependent on it.
This means there should be no transitive dependencies, where a non-prime attribute depends on another non-prime attribute, which in turn depends on the primary key.
Important Key Points:
1. 2NF Requirement:
· A table is in 2NF if it is in 1NF and has no partial dependencies (no non-prime attribute is dependent on part of a composite primary key).
2. No Transitive Dependencies:
· In 3NF, non-prime attributes must depend only on the primary key and not on other non-prime attributes.
3. Direct Dependence on the Primary Key:
· Every non-prime attribute must depend directly and fully on the primary key.
Knowledge Booster:
· Option (b): Incorrect. Non-prime attributes are not dependent on every non-key attribute; they must depend directly on the primary key.
· Option (c): Incorrect. The statement mentions partial dependency, which violates the requirements for 2NF and hence cannot satisfy 3NF.
· Option (d): Incorrect. This condition defines First Normal Form (1NF), not 3NF.
· Option (e): Incorrect. 1NF and the presence of a single candidate key do not ensure 3NF; additional conditions of 2NF and no transitive dependencies are required.