What Is Candidate Key?

The candidate key is a friend you can count on as a natural-born leader. Dependable and modest with an ever-ready handshake and winning smile, the candidate key is the primary key you can take home to Mom and Dad. A candidate key is a unique identifier for a record in a database. It can identify individual rows within the database and is known as the PK (Primary Key) in the relational model. While a super key may contain more than one candidate key, there should never be two candidate keys that occur together in any combination across all tables. A unique identifier can differentiate each record in a table from the others. A candidate key could be a combination of a person's first and last name. If two different people have the same first and last name, that combination is not unique. Adding a date of birth to the candidate key provides information that makes the individual critical. A primary key is used to identify each record in a database. Primary keys are often mandatory and unique. Primary keys are often the foundation for other keys in your database. They are usually recommended as the best option for any additional key referenced in your database and often use numbers, letters, or a combination of both. An attribute or a combination of features uniquely identifies each record. The best way to describe it is with an example: A bank's database is being designed. To uniquely define each customer's account, a combination of the customer's customer's birthdate and a sequential number for each account could be used as the primary key. This might be the best solution if you seek a unique way to identify your candidates. A candidate key is a great way to identify each individual, even if they share the same name and look for similar jobs.