Let us first develop simple DVT Component that will render count of employee for each department using various representation.
I am using following query using standard HR schema.
When you drag/Drop datacontrol VO for pieGraph Grpah for subtype Ring ,It will create following binding in page definition after you provided configuration for graph slices.
When you Drag/Drop graph , It will ask you to provide configuration for Ring , Slices and I gave following.
Here is output of graph when you run the project.
Now you can use same data control object and try various types of graph instead of above.