Now, you are ready to explore the capabilities of the Denodo Platform that make Data Virtualization a powerful tool. In the previous sections you have connected to the CRM database and queried its tables. Customer, customer-type and address data is available within Denodo, so you can start to build a unified view of a customer that will contain the information of the three tables, removing the need for each consumer of the data to create this unified view (derived view).
We create this unified view within the virtualization platform so it can be reused by all clients. Having it defined in a single point will make easier to manage changes to our definition of the customers (for example, if in the future we only will want to expose residential customers to the consuming applications or maybe the source database will be different). With Denodo, you maintain the data definition and your final applications won't require any changes.
The way of doing this unified view of a customer is through a join operation, in the same way as it's done in a traditional relational database.
Let's see an example of the derived view creation process using the Join operation. The starting point is to right-click in the
elements tree and select
New > Join.
This way, an empty Join View panel will be shown in the Administration Tool workspace.
To select the views on which the join operation is going to be executed, you have to drag&drop them from the list of views that appear on the Elements Tree. As input views are added, the schema of the resulting join view is generated automatically.
In our example, you have to follow these steps:
Once these steps are completed, you will have a derived view (virtual, data is not stored in Denodo) that represents the concept of a customer within your organization. This view can be queried in the same way that you did for the base views (check how to in the previous section). Now that this data is defined, your client applications can just retrieve this information directly from the virtualization server without having to define the data combination themselves.
As additional information, Denodo provides a full set of relational operations, in addition to the join, to create new views:
These operations can be used in the same way than the Join operation, you can try yourself!