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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.
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).
An entity–relationship model (ERM) is an abstract conceptual representation of structured data. Entity–relationship modeling is a relational schema database modeling method, used in software engineering to produce a type of conceptual data model (or semantic data model ) of a system, often a relational database , and its requirements in a ...
EXPRESS offers a series of datatypes, with specific data type symbols of the EXPRESS-G notation: [2] Entity data type: This is the most important datatype in EXPRESS. It is covered below in more detail. Entity datatypes can be related in two ways, in a sub-supertype tree and/or by attributes.
Three levels of view are defined in IDEF1X: entity relationship (ER), key-based (KB), and fully attributed (FA). They differ in level of abstraction. The ER level is the most abstract. It models the most fundamental elements of the subject area - the entities and their relationships. It is usually broader in scope than the other levels.
This page was last edited on 23 May 2012, at 03:06 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may apply ...
English: The PDF contains 296 symbols described in the standard ISO 10628-2:2012 titled "Diagrams for the chemical and petrochemical industry — Part 2: Graphical symbols". Symbols are grouped in the same way that the standard does. Since SVG does not support multi-page formatting, individual SVG files have been uploaded.
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