**A set of fields combinations which could be considered for Primary Key.** In [[Relational Databases]], a "Candidate Key" is basically a (set of) field(s) inside a table that _**could**_ unique identify one row (a.k.a. "[[Tuple]]")... but isn't _necessarily_ being used to do that, functionally. Any given table may have multiple Candidate Keys, but only one of them may be chosen as the "[[Primary Key]]". Candidate Keys reveal the possible ways in which a DBA could positively identify a single Tuple. One such way will be chosen & blessed as the "Primary Key". Other sets that would also function are all considered "Alternate Keys". Candidate Keys are just the Primary Key and all sets of possible Alternate Keys. **** # More ## Source [Candidate key](https://en.wikipedia.org/wiki/Candidate_key) ## Related - [[Primary Key]] - [[Relational Databases]]