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Data Modeling

The first step in designing a database is to determine which objects to represent within the database and which of the objects' properties to include. This process is called data modeling. The purpose of a data model is to create a logical representation of the data structure that's used to create a database. Data modeling can encompass an entire organization, a division or department, or a single type of object. Models that deal with objects, rather than the tables that you later create from the objects, are called conceptual data models.

Figure 22.2 illustrates two different approaches (conceptual data models) to database design: the bottom-up approach to create an application database, and the top-down method to develop subject databases. These two approaches, discussed in the following sections, result in databases with quite different structures.


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