By the end of this chapter you will be able to:

• Understand the difference between models and model views
• Drag existing modelling components into a modelling view
• Understand the difference between 'Remove from Model' and 'Permanently Delete' options

In this exercise, you will try some actions that are common when building models, and constructing model views. At the end of the exercise, it is important that you have understood the difference between a model, and a model view.

Drag existing modelling components into a modelling view

1. Create a model with Name: Introduction to Modelling 2
   You will now add the objects you created in exercise 3 to this model:
   1. Open the list of database collectors in the repository.
   2. Find the database collector SOURCE_CUSTOMER_PHONE_NUMBERS - you created this in exercise 3.
   3. Drag this into the model Introduction to Modelling 2.
2. You could add the other objects you created in exercise 3 in a similar way, from the list of datasources and the list of tables respectively. But instead of this, you will add these to the current model view by using the Show Inputs and Show Outputs functions:
   1. Hover over the database collector you have just added to the model.
   2. In the hover menu, press  Show Inputs; the datasource you created will appear.
   3. Hover over the database collector again, and in the tool bar press  Show Outputs; the table you created will appear.
3. In the model window, press Save the model layout.
   Now open the model Introduction to Modelling. If you don't already have this open:
   1. Find the list of Analysis Models in the repository.
   2. Find your model, right click and select Display.

The objects you have just added to Introduction to Modelling 2 are still shown. Models are really just views of a selection of objects in PhixFlow, and they show how they are related. Any object can be shown on as many model views as you like; and objects can be linked to objects that are not shown on a view.

Remove an object from a model view

1. Hover over the table SOURCE_CUSTOMER_PHONE_NUMBERS in the model Introduction to Modelling 2.
2. In the tool bar press  Remove. The table will disappear from the model.
3. Re-add the table to the model using  Show Outputs on the database collector SOURCE_CUSTOMER_PHONE_NUMBERS.

Permanently delete an object

1. Drag the table Practice table from the Repository onto the model Introduction to Modelling 2.
2. Save the new model layout.
3. Right click on Practice table and select Permanently Delete.
4. Once you have deleted the table, press  Refresh on the model.
   
5. The table will have disappeared from the model.
6. Go into the model Introduction to Modelling.
7. Press  Refresh on the model.
   

You will see that the table has disappeared in this model as well. Permanently deleting an object removes it entirely from PhixFlow, and it will no longer appear in any model view.