Select possible entities

You can probably list several entities for your database immediately. Make a preliminary list of all the entities you can identify. Interview the potential users of the database for their opinions about what must be recorded in the database. Determine basic characteristics for each entity, such as “at least one address must be associated with a name.” All the decisions you make about the entities become your business rules. The telephone directory example on page Figure 1 provides some of the business rules for the example in this chapter.

Later, when you normalize your data model, some of the entities can expand or become other data objects. For more information, see Normalize a data model.