Sunday, December 2, 2018

What Is a Data Model, and What It Is Not

“The term data model is used in two distinct but closely related senses. Sometimes it refers to an abstract formalization of the objects and relationships found in a particular application domain, for example the customers, products, and orders found in a manufacturing organization. At other times it refers to a set of concepts used in defining such formalizations: for example concepts such as entities, attributes, relations, or tables. So the "data model" of a banking application may be defined using the entity-relationship "data model". This article uses the term in both senses.”
--Data Model, Wikipedia

What a True Data Model Is

Few practitioners realize that Codd invented the Relational Data Model (RDM) as the first exemplar of a data model, a concept that he formalized in 1980 as follows: