Comparing two tables Customer vs Sales

[#1]

Hi,

I have to do a report showing inactive customers (customers who have not bought in a while) This report, should be filtered by day, month and year.
At my table linking all the customers with sales, the first problem I ran into was that the time needed both tables, so my customer table will add a date from the creation of the client to the present day and my report worked. However, my QVD is very heavy and difficult to query my qvw.

Do you have any other ideas to solve it?

Customer	Sales
CustomerID	Date
Name	CustomerID
	Sale