Create External Model
The Master model (Conceptual Schema) can become quite large and difficult to handle for an end-user or an application team. A team which is only concerned with a subset of the entire model is better off with a submodel (external schema). We create a Submodel for "Finance" which contains only the entities Customer, Payment and Order.
- (1) (not displayed): right click in the Dictionary on the Icon "Schemas", select "Add", Enter the name of the Subschema (Finance) and confirm
- (2) Click on the Subschema (S) perspective: the dictionary pane is removed and the Master pane and the Subschema pain are displayed.
- (3) Click on the Finance icon in the Subschema list
- (4) Select all entities in the Master model which should be allocated to the Finance submodel using Shift/Click
- (5) Drag the selected group to the Finance (Schema) pane and drop it there
- (6) The picture for the submodel was generated and displayed. Notice that all attributes of the selected entities are now also allocated to the entities in the submodel. All relations between the selected entities are also in the submodel. Outside relation (e.g. between Order and OrderItem) are dropped.