Entity–relationship model

entity-relationship modelentity-relationshipEntity-relationship diagramentitiesentityER diagramERDentity relationshipentity relationship modelentity–relationship
An entity–relationship model (or ER model) describes interrelated things of interest in a specific domain of knowledge.wikipedia
212 Related Articles

Entity

entitiesobjectEntity (disambiguation)
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).

Peter Chen

Peter P. ChenDr Peter ChenP.P. Chen
Entity–relationship modeling was developed for database and design by Peter Chen and published in a 1976 paper.
He is a Distinguished Career Scientist and faculty member at Carnegie Mellon University, who is known for the development of the entity-relationship model in 1976.

Database

database management systemdatabasesDBMS
Consequently, the ER model becomes an abstract data model, that defines a data or information structure which can be implemented in a database, typically a relational database.
Another data model, the entity–relationship model, emerged in 1976 and gained popularity for database design as it emphasized a more familiar description than the earlier relational model.

Data modeling

data modellingmodelingmodeled
Consequently, the ER model becomes an abstract data model, that defines a data or information structure which can be implemented in a database, typically a relational database.

Conceptual schema

conceptual data model.cdmconcept-level schema
In the case of the design of an information system that is based on a database, the conceptual data model is, at a later stage (usually called logical design), mapped to a logical data model, such as the relational model; this in turn is mapped to a physical model during physical design.

Weak entity

Every entity (unless it is a weak entity) must have a minimal set of uniquely identifying attributes, which is called the entity's primary key.
In entity relationship diagrams (ER diagrams), a weak entity set is indicated by a bold (or double-lined) rectangle (the entity) connected by a bold (or double-lined) type arrow to a bold (or double-lined) diamond (the relationship).

Metadata

meta datameta-datacommunications metadata
The design of structural metadata commonality using a data modeling method such as entity relationship model diagramming is important in any data warehouse development effort.

Barker's notation

Barker–Ellis
As an aside, the Barker–Ellis notation, used in Oracle Designer, uses same-side for minimum cardinality (analogous to optionality) and role, but look-across for maximum cardinality (the crows foot). Crow's foot notation, the beginning of which dates back to an article by Gordon Everest (1976), is used in Barker's notation, Structured Systems Analysis and Design Method (SSADM) and information technology engineering.
Barker's notation refers to the ERD notation developed by Richard Barker, Ian Palmer, Harry Ellis et al. whilst working at the British consulting firm CACI around 1981.

Logical schema

logical data modelschemadatabase schema
In the case of the design of an information system that is based on a database, the conceptual data model is, at a later stage (usually called logical design), mapped to a logical data model, such as the relational model; this in turn is mapped to a physical model during physical design.

Cardinality (data modeling)

cardinalitycardinalitiescardinality constraint
Certain cardinality constraints on relationship sets may be indicated as well.
The entity–relationship model proposes a technique that produces entity–relationship diagrams (ERDs), which can be employed to capture information about data model entity types, relationships and cardinality.

Three-schema approach

Three schema approachconceptual view3-schema architecture

Anchor modeling

It provides a graphical notation used for conceptual modeling similar to that of entity-relationship modeling, with extensions for working with temporal data.

Data structure diagram

Bachman diagramBachman DiagramsBachman
The lines, arrows and crow's-feet of some diagrams owes more to the earlier Bachman diagrams than to Chen's relationship diagrams.
The data structure diagrams is a predecessor of the entity-relationship model (E-R model).

Enhanced entity–relationship model

enhanced
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.

IDEF1X

IDEF1logical database design technique
The theoretical roots for this approach stemmed from the early work of Edgar F. Codd on Relational model theory and Peter Chen on the entity-relationship model.

Ontology (information science)

ontologyontologiesOntology (computer science)
Some ER models show super and subtype entities connected by generalization-specialization relationships, and an ER model can be used also in the specification of domain-specific ontologies.
In computer science and information science, an ontology encompasses a representation, formal naming and definition of the categories, properties and relations between the concepts, data and entities that substantiate one, many or all domains of discourse.

Object-role modeling

NIAMORMENALIM
ORM is attribute-free: unlike models in the entity–relationship (ER) and Unified Modeling Language (UML) methods, ORM treats all elementary facts as relationships and so treats decisions for grouping facts into structures (e.g. attribute-based entity types, classes, relation schemes, XML schemas) as implementation concerns irrelevant to semantics.

Computer-aided software engineering

CASECASE toolComputer Aided Software Engineering
Many of the consultants at CACI (including Richard Barker) subsequently moved to Oracle UK, where they developed the early versions of Oracle's CASE tools, introducing the notation to a wider audience.

Associative entity

junction tableAssociative Entitiesassociation data mapping
An associative entity is a term used in relational and entity–relationship theory.

Unified Modeling Language

UMLUnified Modelling Languageinteraction diagram
As with database Chen, Bachman, and ISO ER diagrams, class models are specified to use "look-across" cardinalities, even though several authors (Merise, Elmasri & Navathe amongst others ) prefer same-side or "look-here" for roles and both minimum and maximum cardinalities.

Structured entity relationship model

Structured-Entity-Relationship-Model
The SERM (structured entity relationship model) is an amplification of the ERM which is commonly used for data modeling.

Merise

In Merise, Elmasri & Navathe and others there is a preference for same-side for roles and both minimum and maximum cardinalities.

Enterprise architecture framework

frameworkarchitectural frameworkreference model
The basic data model type which is most commonly used is called merda (master entity relationship diagrams assessment, see entity-relationship model).

Information engineering

information technology engineeringData EngineeringInformation Technology
Crow's foot notation, the beginning of which dates back to an article by Gordon Everest (1976), is used in Barker's notation, Structured Systems Analysis and Design Method (SSADM) and information technology engineering.