Database Normalisation Questions Medium
In the context of database normalization, a candidate key is a minimal set of attributes that can uniquely identify each tuple (or row) in a relation (or table). It means that no subset of the candidate key can also uniquely identify the tuples. In other words, a candidate key is a unique identifier for a tuple without any redundant attributes.
On the other hand, a superkey is a set of attributes that can uniquely identify each tuple in a relation, but it may also contain additional attributes that are not necessary for uniqueness. In other words, a superkey is a superset of a candidate key, meaning it can include redundant attributes.
To summarize, the main difference between a candidate key and a superkey is that a candidate key is a minimal set of attributes that uniquely identifies tuples without any redundancy, while a superkey is a set of attributes that can uniquely identify tuples but may contain additional attributes that are not necessary for uniqueness.