Data Modelling
Data Modelling
Data modelling diagrams are created using the diagram type, Entity Relationship Diagram.
Entity Relation diagrams contain Entity objects. Existing Entities can be searched for, by using the magnifying glass icon, and then selected to be added to the list of objects in the diagram's Dataset. The Entities listed in the diagram's Dataset will be visible after clicking on the DIAGRAM tab at the top of the page.
Entities can be added to the diagram by dragging the Entity, from the palette on the left hand side, onto the diagram.
The Add Entity dialog will expect a new name to be entered, or an existing name to be selected.
Clicking OK or pressing the Enter key, will add the Entity to the diagram. Selecting an existing name will add that Entity to the diagram.
It is expected that an Entity will 'contain' Attribute objects. To add new Attributes, click the + button in the top right corner of the Entity.
A Name is required, before clicking the OK button. The example above, shows an ID attribute, identified as the Primary Key of Customer.
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Attribute objects are not to be confused with property attributes. An Attribute object will have its own property attributes, such as "Is Primary Key Of". |
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Attributes are displayed inside their Entity, but the model is not updated until the diagram is saved. |
An Attribute object will be created for each Attribute. The name will be prefixed by the Entity name, and separated by a period. e.g. Customer.ID
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Save the diagram regularly to ensure that the diagram and model are updated. |
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Clicking away from a diagram without saving it will lose all recent changes. |
Entities can be related to each other by drawing a relationship. A Relationship object will be created to further describe this relationship.
The Add Relationship dialog will require a Name to be entered before clicking OK.
The example above describes the places relationship between a Customer and an Order. The Type of relationship is Parent/Child to indicate that an Order must have one, and only one, Customer to exist. The Child Cardinality of Zero or many indicates that a Customer can exist without having placed any orders. The relationship is not Identifying, so the Order will not require the Customer's Key as part of its own Key. A Relationship object will be created with the name Customer places order.
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The Relationship can be edited by right clicking, and selecting the Edit Relationship option, but its Type cannot be changed. |
The relationship will then be displayed on the diagram using "Crow's Feet" notation.
Note that the foreign key Customer.ID, has been automatically added to Order.
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Entity objects can be edited in the same way as other objects, while Attribute and Relationship objects will have restrictions on their update |
Examples of Views
Examples of Views
Organization Viewpoint
Organization Viewpoint
The Organization viewpoint focuses on the (internal) organization of a company. It can be represented hierarchically or as a box in box view.
The Organization viewpoint is used to identify competencies, authority, and responsibilities in an organization.
The object types for the organization viewpoint are:
Business actor, Business collaboration, Business interface, Business role, and Location.
Actor Co-operation Viewpoint
Actor Co-operation Viewpoint
The Actor Co-operation viewpoint focuses on the relationships of actors with each other and their environment.
This viewpoint is also used to show how a number of co-operating actors or application components, work together to realize a business process.
The object types for this viewpoint are:
Application service, Application interface, Application component, Business actor, Business collaboration, Business interface, Business role, and Business service.
