A Level Computer Science OCR Practice Exam

In Second Normal Form (2NF), what must every attribute depend on?

1. Any attribute in the table

2. The primary key

3. Only the non-key attributes

4. The relationship with other tables

The correct answer is: The primary key

In Second Normal Form (2NF), every attribute in a database table must depend on the entire primary key. This means that for a table to be in 2NF, it must be free from partial dependency, where an attribute is dependent on only a part of a composite primary key. Therefore, all non-key attributes must be fully functionally dependent on the whole primary key to satisfy 2NF requirements. By ensuring that all attributes depend on the primary key, it helps to eliminate redundancy and the potential for anomalies during data manipulation, such as insertion, deletion, or updating of records. This step is essential in database normalization as it promotes the integrity and efficiency of data storage and management. Hence, the correct answer highlights the importance of the primary key in determining the dependencies of other attributes within a table in the context of normalization.