"A common way to organize, think about, or discuss the elements of the 'real world' that a database design will represent, by dividing them into entities and relationships." (Bill Pribyl & Steven Feuerstein, "Learning Oracle PL/SQL", 2001)
"A type of conceptual data model that represents structured data in terms of entities and relationships. An entity-relationship diagram can be used to represent information objects and their relationships visually. Because the constructs used in the entity-relationship model can easily be transformed into relational tables, this type of model is often used in database design." (J P Getty Trust, "Introduction to Metadata" 2nd Ed., 2008)
"A data model that is used to represent data in its purest form and to define relationships between different entities." (Laura Reeves, "A Manager's Guide to Data Warehousing", 2009)
"A technique for representing entity relationships that is independent of any specific data model and any specific software." (Jan L Harrington, "Relational Database Design and Implementation" 3rd Ed., 2009)
"A conceptual data model involving entities, relationships among entities, and attributes of those entities." (Toby J Teorey, ", Database Modeling and Design" 4th Ed., 2010)
"A data model developed by P. Chen in 1975. It describes relationships (1:1, 1:M, and M:N) among entities at the conceptual level with the help of ER diagrams." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)
"An abstract and conceptual representation of data. Entity-relationship model consists of a set of entities, characterized by attributes and linked by relationships." (International Qualifications Board for Business Analysis, "Standard glossary of terms used in Software Engineering", 2011)
"1.Generally, a record-based data modeling scheme that focuses on entities and relationships in the presentation of data model diagrams, thus suppressing the display of attributes. A true ER model allows multi-valued data items and repeating groups of items (nested relations, thus violating first normal form), retains M:N relationships, attributed relationships, subtypes/supertypes, ternary and higher-order relationships, none of which can be represented directly in a relational data model. A true ER model generally excludes (defers) the representation of entity identifiers and foreign keys. Originally proposed and named by Peter Chen (1976). 2.In relational modeling, the most popular style of data model, defining entities and the business relationships between the entities. Some more detailed models include also some of the attributes of these entities, usually those involved in the relationships as keys." (DAMA International, "The DAMA Dictionary of Data Management", 2011)
"A data management approach that graphically represents relationships between data. This allows developers to create new relationships between data sources without complex programming." (Marcia Kaufman et al, "Big Data For Dummies", 2013)
"A logical view of data within a system, representing the entities in the system as well as relationships among the entities, attributes of the entities, and attributes of the relationships." (IEEE 610.5-1990)
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