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The enhanced entity–relationship (EER) model (or extended entity–relationship model) in computer science is a high-level or conceptual data model incorporating extensions to the original entity–relationship (ER) model, used in the design of databases.
Diagrams created to represent attributes as well as entities and relationships may be called entity-attribute-relationship diagrams, rather than entity–relationship models. An ER model is typically implemented as a database. In a simple relational database implementation, each row of a table represents one instance of an entity type, and each ...
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.
Data-Flow Diagram example [19] A data-flow diagram (DFD) is a graphical representation of the "flow" of data through an information system. It differs from the flowchart as it shows the data flow instead of the control flow of the program. A data-flow diagram can also be used for the visualization of data processing (structured design).
For example, as soon as you want to find seasonal or geographical trends in the sales of the item, you need information from the related Order record. An order would not exist without a product and a person to create the order, so it could be argued that an order would be described as a weak entity and that products ordered would be a ...
Examples of predefined UML stereotypes are Actor, Exception, Powertype and Utility. Structure diagram; Superstate - construct allowing several States which share common Transitions and Internal Activities; Swim lane - synonym for Partition; System model - The logical UML model being represented through one or more UML diagrams
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. One owner could have many cars, one-to-many. In a relational database, a one-to-many relationship exists when one record is related to many records of another table. A one-to ...
A car, for example, has an engine, a transmission, etc., and the engine has components such as cylinders. (The permissible substructure for a given class is defined within the system's attribute metadata, as discussed later. Thus, for example, the attribute "random-access-memory" could apply to the class "computer" but not to the class "engine".)