comparing total data with data in actual selection

[tursic]

Hello.

I have customers (with customer_id) and orders (with order_id).
Every customer belongs to a salesman.

Now I want to show all customers of the selected salesman, which have no orders in the selected period.

Is that possible?

I thought, it may work by comparing a list of all customers of the salesman with a list of customers in the actual selection.

But how can I get a list of all data regardless the selection, and how can I compare it with the actual data?
As far as I know, keywords like 'total' only work with calculations like 'sum'.

Can anybody help?

[GaryGiles]

For your Customer dimension, try this:

Aggr(Only({$<customer_id={"=count(order_id)=0"}>} customer_id), customer_id)

This will give you customers with no orders.  If a selection is made in the salesman and/or period field, the criteria of {"=count(order_id)=0"} will filter according to those selections and render the appropriate customers.  Note: it will also filter on any other fields that you filter on.  

[tursic]

Thanks for the answer.

This works, when selecting a salesman, but when I select a period, there is no data at all.