Database Normalisation Questions Medium
In database normalization, candidate keys refer to the attributes or combination of attributes that can uniquely identify each tuple or row in a relation or table. These candidate keys are essential in the process of database normalization as they help eliminate data redundancy and ensure data integrity.
A candidate key must satisfy two properties: uniqueness and minimality.
Uniqueness means that each candidate key value must be unique and cannot be duplicated within the table. This ensures that each tuple can be uniquely identified using the candidate key.
Minimality means that no subset of the candidate key can also uniquely identify a tuple. In other words, removing any attribute from the candidate key would result in losing the uniqueness property. This ensures that the candidate key is the smallest possible set of attributes that can uniquely identify a tuple.
It is important to note that a relation or table can have multiple candidate keys. These candidate keys can be either single attributes or a combination of multiple attributes. The primary key is chosen from the candidate keys to uniquely identify each tuple in the table.
By identifying and utilizing candidate keys during the normalization process, we can ensure that the database is structured efficiently, with minimal redundancy and maximum data integrity.