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An entity–relationship model (or ER model) describes interrelated things of interest in a specific domain of knowledge. A basic ER model is composed of entity types (which classify the things of interest) and specifies relationships that can exist between entities (instances of those entity types).
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.
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ER/Studio: Logical, physical, ETL IDEF1X, IE (Crow’s feet) Yes Yes Update database and/or update model ER/Studio Repository and Team Server (formerly Portal/CONNECT) for web based publishing collaboration and model management, with Business Glossary as standard. MagicDraw: Conceptual, Logical & Physical + MDA Transform of Logical to Physical
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.
The ER model is the basis for IBM's Repository Manager/MVS and DEC's CDD/Plus. Chen's original paper [ 3 ] is commonly cited as the definitive reference for entity relationship modeling though the concept of object relationship had been developed a year earlier by Schmid and Swenson as reported in the 1975 ACM SIGMOD Proceedings [1] .
ER/Studio has a computer-aided software engineering tool (or CASE tool). [2] Users can utilize ER/Studio as a way to take conceptual data model and create a logical data model that is not dependent on a specific database technology. [3] This schematic model can be used to create the physical data model.
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.