Search results
Results from the WOW.Com Content Network
A candidate key is a minimal superkey, [1] i.e., a superkey that doesn't contain a smaller one. Therefore, a relation can have multiple candidate keys, each with a different number of attributes. [2] Specific candidate keys are sometimes called primary keys, secondary keys or alternate keys.
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 ...
In database design, a composite key is a candidate key that consists of two or more attributes, [1] [2] [3] (table columns) that together uniquely identify an entity occurrence (table row). A compound key is a composite key for which each attribute that makes up the key is a foreign key in its own right.
Usually one candidate key is chosen to be called the primary key and used in preference over the other candidate keys, which are then called alternate keys. A candidate key is a unique identifier enforcing that no tuple will be duplicated; this would make the relation into something else, namely a bag, by violating the basic definition of a set ...
An important notion in this context is a candidate key, defined as a minimal set of attributes that functionally determine all of the attributes in a relation. The functional dependencies, along with the attribute domains , are selected so as to generate constraints that would exclude as much data inappropriate to the user domain from the ...
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.
If you've been having trouble with any of the connections or words in Tuesday's puzzle, you're not alone and these hints should definitely help you out. Plus, I'll reveal the answers further down. ...
The table containing the foreign key is called the child table, and the table containing the candidate key is called the referenced or parent table. [4] In database relational modeling and implementation, a candidate key is a set of zero or more attributes, the values of which are guaranteed to be unique for each tuple (row) in a relation.