Search results
Results From The WOW.Com Content Network
An associative entity is a term used in relational and entity–relationship theory. A relational database requires the implementation of a base relation (or base table) to resolve many-to-many relationships. A base relation representing this kind of entity is called, informally, an associative table. An associative entity (using Chen notation)
For example, think of A as Authors, and B as Books. An Author can write several Books, and a Book can be written by several Authors. In a relational database management system, such relationships are usually implemented by means of an associative table (also known as join table, junction table or cross-reference table), say, AB with two one-to-many relationships A → AB and B → AB.
An entity–relationship model ... For example, an employee entity might have a Social Security ... Associative entity – Term in relational and entity ...
The foreign key is typically a primary key of an entity it is related to. The foreign key is an attribute of the identifying (or owner, parent, or dominant) entity set. Each element in the weak entity set must have a relationship with exactly one element in the owner entity set, [1] and therefore, the relationship cannot be a many-to-many ...
The columns enumerate the various attributes of the entity (the employee's name, address or phone number, for example), and a row is an actual instance of the entity (a specific employee) that is represented by the relation. As a result, each tuple of the employee table represents various attributes of a single employee.
Pages in category "Entity–relationship model" ... Associative entity; S. Supra-entity This page was last edited on 16 June 2012, at 11:38 (UTC). ...
For example, we can regard a booking as either an entity that associates a person with a flight, or as an entity that designates a person and designates a flight. Hence a designative entity must contain at least one designation whereas an associative entity must contain at least two designations.
In systems analysis, a one-to-many relationship is a type of cardinality that refers to the relationship between two entities (see also entity–relationship model). For example, take a car and an owner of the car. The car can only be owned by one owner at a time or not owned at all, and an owner could own zero, one, or multiple cars.