In the last lesson, you created a physical data model and
an overview diagram of the data model. You can use diagrams in the
workbench to visualize and modify data models.
The default overview diagram contains all objects that
are contained in the GOSALESDW schema. However, when you are working
with a large data model, you can create simplified overview diagrams
so that they contain only the objects that you are interested in.
You can create multiple diagrams for one data model, each with different
objects.
You want to add a column to the EMP_EMPLOYEE_DIM table
to document the middle initial of employees. Before you add the column,
you should create a simple overview diagram that will help you to
visualize the changes to your data model.
In this lesson, you
will create a new overview diagram that contains the following tables
from the GOSALESDW schema:
- EMP_EMPLOYEE_DIM
- EMP_POSITION_LOOKUP
- EMP_TERMINATION_LOOKUP
- GO_GENDER_LOOKUP
To create a simple overview diagram:
- Make sure that the sample_model.dbm file is still open in the physical data model editor. To view or modify objects in a data model, the model must always
be open in the editor.
- In the Data Project Explorer, locate
the GOSALESDW schema node: .
- Create a new overview diagram. Expand the GOSALESDW schema and right-click the Diagrams folder, then select New Overview Diagram.
Tip: As an alternative to these steps, you can also select New Blank Diagram, and then drag and drop objects from
the Data Project Explorer to the diagram surface.
- In the window that opens, specify the following settings:
- Diagram name
- Type myGOSALESDW.
- Infer implicit relationships
- Do not select the check box.
- Include selected elements
- Select the check box next to the following schemas:
- EMP_EMPLOYEE_DIM
- EMP_POSITION_LOOKUP
- EMP_TERMINATION_LOOKUP
- GO_GENDER_LOOKUP
The window will look like the following
image.
- Click OK to create the simplified
overview diagram.
The new myGOSALESDW diagram opens in the diagram editor and
is displayed in the
Data Project Explorer in
the
Diagrams folder under the GOSALESDW schema.
Tip: Move the tables in the diagram closer together so that
you can see them all at the same time. You can use the shaded box
in the Outline view to move the focus in the
diagram, then highlight diagram objects and drag them to move them.