Data models are a group of conceptual tools to describe data those which (the models of data) they are compound on one part semantic (it has restrictions of integrity) a part of manipulation (it has operations that manipulate structural part) and a structural part (it has objects and structures of data) We meet with 5 types of models: Real world, conceptual world, databases, structures of data and physical storage. In data base model we have 4 models: Hierarchy data-model, net data-model, relational data-model and object-oriented data model. The entity-relationship data model is used for a lot of people actually.
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