8.0 Tutorials

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First steps - Execution of Queries

After creating the base views in the previous section, we are ready to query our Data Virtualization server to retrieve the data from our CRM. Let's learn how to issue queries to the Denodo server.

There are several ways to perform the execution of a view, we will use the "client" view for this example, from the Administration Tool:

Context menu

To use the Context menu you have to:

  1. Click on the name of the view in the Elements Tree panel and click on More Options(dotted lines)
  2. Select "Execute...".
  3. Then click the Execute button at the bottom of the panel to send the current sentence (shown at the top) to the Denodo server.

View detail window

In this case you have to:

  1. Double-click on the name of the view.
  2. Press the Execution panel button at the top of the workspace.

VQL shell

Another option is to use the VQL Shell Client:

  1. In the Menu Bar, go to Tools > VQL Shell
  2. Click on the name of the view and choose More Options > select "VQL Shell > Select ..." (a sentence is created in the top-right panel).
  3. Then click the Execute button.

Show results

In the three examples above, a simple query is executed:

SELECT * FROM client

CODE

After receiving that query, the Denodo server will create a physical query plan to query the data sources (in this case, your MySQL database) and get the results:

You can filter the results obtained in the output using a WHERE condition in the sentence. This can be done using the graphical interface in the execution window shown when using the Context menu or View detail window options.

In this panel,you have specify the where condition. Click on Ctrl+space for autocomplete

To summarize, now you have learned how to execute queries over Denodo views and how the server is querying the source database in real-time to return the results. In the next section, we are going to learn how to create new views using combinations between existing Denodo views.