Describe the candidate key functions ?
Candidate Key and Alternate Key: In some instances, an entity will have more than one attribute which can serve as a primary key. Any key or minimum set of keys which could be a primary key is known as a candidate key. Ones candidate keys are identified, one of them is chosen as primary key. The choice of Primary key is based on guaranteed uniqueness and minimalism.
Candidate keys that are not chosen as the primary key are known as alternate keys.