Search results
Results from the WOW.Com Content Network
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 ...
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 ...
Domain-key normal form (DK/NF or DKNF) is a normal form used in database normalization which requires that the database contains no constraints other than domain constraints and key constraints. A domain constraint specifies the permissible values for a given attribute, while a key constraint specifies the attributes that uniquely identify a ...
A Super key, located between the Control key and the Alt key, on an ISO style PC keyboard. Super key ( ) is an alternative name for what is commonly labelled as the Windows key [1] or Command key [2] on modern keyboards, typically bound and handled as such by Linux and BSD operating systems and software today.
Download as PDF; Printable version ... move to sidebar hide. Super key may refer to: Super key (keyboard button) ... modifier key on keyboards; Superkey, database ...
Codd's twelve rules [1] are a set of thirteen rules (numbered zero to twelve) proposed by Edgar F. Codd, a pioneer of the relational model for databases, designed to define what is required from a database management system in order for it to be considered relational, i.e., a relational database management system (RDBMS).
Table inheritance also avoids or reduces the need for supplementary tables whose primary key is a foreign key to another table, and thus can simplify many queries and updates. have a Historian [ 6 ] module to allow large volumes of times-series data to be captured, stored, archived and queried in an efficient fashion.
In computer science, domain relational calculus (DRC) is a calculus that was introduced by Michel Lacroix and Alain Pirotte as a declarative database query language for the relational data model.