Database Normalisation Questions Long
The role of unique keys in database normalization is to ensure data integrity and eliminate data redundancy. Unique keys are used to uniquely identify each record in a table and enforce the uniqueness constraint on one or more columns.
In the context of normalization, unique keys play a crucial role in achieving the desired level of normalization, specifically in the first three normal forms (1NF, 2NF, and 3NF).
1. First Normal Form (1NF): Unique keys are used to ensure that each attribute within a table contains only atomic values, meaning that it cannot be further divided. By enforcing unique keys, we eliminate the possibility of storing duplicate values in a single attribute, thus achieving 1NF.
2. Second Normal Form (2NF): Unique keys are used to identify functional dependencies within a table. Functional dependencies occur when an attribute depends on a subset of the unique key rather than the entire key. By identifying and separating such dependencies into separate tables, we achieve 2NF.
3. Third Normal Form (3NF): Unique keys are used to eliminate transitive dependencies within a table. Transitive dependencies occur when an attribute depends on another attribute that is not part of the unique key. By identifying and separating such dependencies into separate tables, we achieve 3NF.
Overall, unique keys play a vital role in ensuring data integrity by preventing duplicate values and enforcing the uniqueness constraint. They also help in identifying functional and transitive dependencies, which are essential for achieving higher levels of normalization. By properly utilizing unique keys, we can design a well-structured and efficient database schema.