entity-relationship diagram
<data, database, specification>
A visual representation of an entity-relationship model.
An entity-relationship diagram has a box for each entity, containing its properties, and lines between boxes for relationships. The ends of the lines are labelled to show the type of relationship - one-to-one, one-to-many or many-to-many.Last updated: 2019-11-03
entity-relationship model
<data, database, specification>
The most common kind of data modelling, proposed by Peter P. Chen in 1976, in which a database is divided into "entities" and "relations".
Part of capturing the requirements of an application is defining the entities involved and their relationships. Together, these form an entity-relationship model. Entities are the kinds of things or concepts the application deals with, e.g. products, customers, sales transactions. A relationship connects two entities and says how many instances of each participate in the relationship - one-to-one, one-to-many or many-to-many. Entities and some relationships correspond to database tables. A table corresponding to a relationship is also known as a "join table" after the join database operation. A model is represented graphically as an entity-relationship diagram. ["The entity-relationship model: toward a unified view of data", P.P. Chen, ACM Transactions on Database Systems 1:1 pp 9-36, 1976].Last updated: 2019-11-03
Nearby terms:
entity ♦ entity-relationship diagram ♦ entity-relationship model
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