Group by on view

Hi all,

I have created a view in which i have dragged 3 tables into my metadatasources : VendTable, Vendinvoicejour and vendinvoicetrans.

I have dragged the selected fields in view's fields which I want to display.

Now i want to apply GROUP BY on a field and COUNT on another and the code to be written in class. So how can i write in runnable class and connect it to view? Because i can use 3 tables and i wrote the code. But here i have to use the view so how to do that in class?