A second normal form does not permit partial dependency between a non-prime attribute and the relation key.


The concept of normalization in database design helps in organizing data efficiently and eliminates data redundancy. Normalization is categorized into different normal forms, such as first normal form (1NF), second normal form (2NF), third normal form (3NF), and so on. Each normal form has certain rules and restrictions that need to be followed for achieving a well-structured and efficient database design.


The second normal form (2NF) builds upon the rules of 1NF and introduces additional requirements for eliminating partial dependencies. In a relation to be in 2NF, it must meet the following conditions:
1. It should already be in 1NF.
2. It should not have any partial dependencies.


Partial dependency refers to a situation in which a non-prime attribute depends on only a part of the primary key, rather than the entire key. In other words, a non-prime attribute is functionally dependent on a subset of the primary key attributes.


In the context of the given question, a second normal form (2NF) does not permit partial dependency between a non-prime attribute and the relation key. This means that a non-prime attribute cannot be functionally dependent on only a part of the primary key.

For example, consider a relation called "Employees" with attributes like Employee_ID (primary key), Employee_Name, and Department. Let's assume that the primary key is Employee_ID. Now, if the Department attribute is functionally dependent on only a subset of the primary key, such as the first two digits of the Employee_ID (which represents the department code), it would violate the 2NF.

To comply with the 2NF, the attribute Department must be functionally dependent on the entire primary key, i.e., the Employee_ID. This means that the Department attribute should be determined by the Employee_ID alone, not by a subset of it.


In conclusion, the second normal form (2NF) does not permit partial dependency between a non-prime attribute and the relation key. This restriction ensures that the database design is free from redundancy and anomalies, leading to better data integrity and efficiency.