A software application typically stores business information in files and databases. Data models are a logical representation of the business processes in a organization. They define how the business interacts with people, places, and things. The data model is used as a reference point for determining the rules of relationships between entities within an organization.
The data model creation process is divided into three primary stages. These are domain models, logical models, and physical models. Each stage is completed in a progression ending with the physical model, which represents the actual structure of the database.
The design of the domain model is the first step in creating a data model. This is a high-level view of the business units within an organization and their relationships to each other. Domain data models define the conceptual relationship between organizations and the processes required to complete a business function. An example of a domain model is the relationship between the ordering of a product and the effect the order has on the shipping department.
The enterprise domain model is typically a very high-level view of the organization and does not require the exact details on each type of business requirement. It is important, however, to include all impacted business units within the domain model design. This high-level design is necessary for the project team to understand the detail functions that are required to complete business functions.
Logical data models are the versions of data models that represent the actual business requirements of a company. These models are designed based on the high-level domain models of specific business units within an organization. A sound logical design is critical to create the physical database. This process must clearly define the data elements that are necessary to complete a specific business requirement. Logical data models include how data will be accessed and the relationships between entities within a business process.
A good example of a logical data model could be a modeling of customers for a telephone company. Each customer has a specific name, phone number, address, and phone features. The logical data model would provide the relationships between these types of elements including how the information would be reported and retrieved.
The final layer of data models is the physical data model. This is the area of data models that is used in creating the actual database. The physical data model is the database-specific blue print, which defines how data will be stored within the software application.