Find customers IN, NOT IN from two transaction tables using DAX

Question

I have two identical fact (sales) tables in Power Pivot. I need to classify customers in 3 categories.
Existing in both tables
Existing exclusively in table 1
Existing exclusively in table 2
What approach do I choose? UNION both the tables in model or keep them as separate tables? Also, what code is to be written to classify the customers in these 3 categories? I need to do Power View reporting on the categories - Distinct Customers, SalesAmt,
Sales Volume etc.
Thanks, Ashish Singh

Answer 1

Try these sollutions:
1.You can append both tables using Power Query ad-in. Even if a list of customers change in any of your tables you will not have to manually correct them in model. Refreshing Power Query table allow to have always updated data in model. Also if both tables
are differ but have a common column as "customers" that's enough to get appendable list of customers. Power Query allows to get distinct values without duplicates. Created table can be linked as a table to your Powerpivot model. No measures are nessesary.
You should receive a simple table with distinct customers names. Lets call it "List of all custumers"
To receive exclucive lists create relations between Table1 and Table2 using "List of all custumers". Now you can use all you need in one pivot table.
2. You can do the same without Power Querry but your data will not be autmaticaly refresh. Appendable table with customers list can be created manualy. This case also not require any formulas or measures.
Of course you can also try Greg's solution
Gordonik