Again, reality has failed to deliver on the promise. Some think that these groups stand between the developers and application delivery, placing unnecessary constraints on developers' designs. In other cases, however, firms have seen the value of having database models serve as a common framework within which new applications can be designed and older applications integrated. Models have also proved useful to organizations trying to integrate many heterogeneous systems developed over time by design ers and developers who may be long gone from the corporate environment. A model is an abstract representation of a real object or environment.
Data modeling is the practice of designing a database using a series of related models.
Next, use this conceptual model to derive a logical data model that captures more detail, but in an implementation-independent way. The first step is, in many ways, the most time-consuming. You begin by collecting data and reviewing business procedures and practices to ascertain the business requirements of the application. These requirements lead to the identification and definition of entities and relationships essential to the business activities being represented. In the conceptual model, you should figure out how you're going to distinguish instances of each entity type.