HOPEX Information Architecture > Data Architecture > Modeling Data dictionaries > Data Model
Data Model
 
Summary of Concepts
Data model
Data diagram
Building a data model
Creating a Data Model
Creating a Data Diagram
Entities
Creating an entity
Attributes
Creating attributes
Inherited attributes
Associations
Creating an Association
Defining association roles (ends)
Multiplicities
Aggregation
Composition
Reflexive Associations
“N-ary” Association
Constraints
Normalization Rules
First Normal Form
Second Normal Form
Third Normal Form
Generalizations
What is a generalization?
Multiple sub-entities
Multiple inheritance
Creating a generalization
Discriminator
Entity Identifier
Identification by an attribute
Data Model Mapping
Functional Objectives
Running the mapping editor
Creating a mapping
Deleting a mapping
Mapping details
Example of mapping between data models
Data modeling consists of identifying the entities representing the activity of the company, and defining the associations existing between them. The entities and associations in the data diagram associated with a sector of the company must be sufficient to provide a complete semantic description. In other words, one should be able to describe the activity of a company by using only these entities and associations.
This does not mean that each word or verb used in this explanation corresponds directly to an object in the data diagram. It means that one must be able to state what is to be expressed using these entities and associations.
Data model specification is often considered the most important element in modeling of an information system.
To help you describe logical data, HOPEX Information Architecture offers a simple notation, based on the data model.
Summary of Concepts
Data model
A data model is used to represent the static structure of a system, particularly the types of objects manipulated in the system, their internal structure, and the relationships between them.
A data model is a set of entities with their attributes, the associations existing between these entities, the constraints bearing on these entities and associations, etc.
Data diagram
A data diagram is a graphical representation of a model or of part of a model.
A data diagram is represented by:
• Entities, which represent the basic concepts (customer, account, product, etc.).
• Associations, which define the relationships between the different entities.
• Attributes, which describe the characteristics of entities and, in certain cases, of associations.
The attribute or set of attributes that enables unique identification of an entity is called an identifier.
The data diagram also contains multiplicity definitions.