Data modeling: Difference between revisions

Revision as of 17:02, 25 June 2023

Revision as of 19:09, 22 July 2023

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* Bottom-up models or View Integration models are often the result of a [[reengineering (software)|reengineering]] effort. They usually start with existing data structures forms, fields on application screens, or reports. These models are usually physical, application-specific, and incomplete from an [[enterprise architecture|enterprise perspective]]. They may not promote data sharing, especially if they are built without reference to other parts of the organization.<ref name="SIG97"/>

* Top-down [[logical data model]]s, on the other hand, are created in an abstract way by getting information from people who know the subject area. A system may not implement all the entities in a logical model, but the model serves as a reference point or template.<ref name="SIG97"/>

Sometimes models are created in a mixture of the two methods: by considering the data needs and structure of an application and by consistently referencing a subject-area model. Unfortunately, inIn many environments the distinction between a logical data model and a physical data model is blurred. In addition, some [[Computer-aided software engineering|CASE]] tools don't make a distinction between logical and [[physical data model]]s.<ref name="SIG97"/>

=== Entity–relationship diagrams ===