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A candidate key, or simply a key, of a relational database is any set of columns that have a unique combination of values in each row, with the additional constraint that removing any column could produce duplicate combinations of values. A candidate key is a minimal superkey, [1] i.e., a superkey that does not contain a smaller one. Therefore ...
A candidate key (or minimal superkey) is a superkey that can't be reduced to a simpler superkey by removing an attribute. [ 3 ] For example, in an employee schema with attributes employeeID , name , job , and departmentID , if employeeID values are unique then employeeID combined with any or all of the other attributes can uniquely identify ...
Candidate key. A candidate key is a superkey that cannot be further subdivided to form another superkey. A superkey holds as a candidate key for a relation universe if it holds as a superkey for and there is no proper subset of that also holds as a superkey for .
The candidate keys of the table are: {Person, Shop type}, {Person, Nearest shop}. Because all three attributes are prime attributes (i.e. belong to candidate keys), the table is in 3NF. The table is not in BCNF, however, as the Shop type attribute is functionally dependent on a non-superkey: Nearest shop.
Every non-trivial functional dependency either begins with a superkey or ends with a prime attribute (attributes depend only on candidate keys) [5] Every non-trivial functional dependency either begins with a superkey or ends with an elementary prime attribute (a stricter form of 3NF)
Former presidential candidate Nikki Haley has demanded a Super PAC’s project, Haley Voters for Harris, stop using her name. “Kamala Harris and I are total opposites on every issue.
In relational database management systems, a unique key is a candidate key. All the candidate keys of a relation can uniquely identify the records of the relation, but only one of them is used as the primary key of the relation. The remaining candidate keys are called unique keys because they can uniquely identify a record in a relation.
Specifically, the Enhanced Presidential Security Act — introduced by Reps. Mike Lawler, R-N.Y., and Ritchie Torres, D-N.Y. — would require the Secret Service to “apply the same standards for ...