and the same logic then showing the previous 12 months before that. as you can see from the application as attached, if i select purchase dates from Dec-18 (dynamic 12 months back from the Max date per customer) to Nov-19.
for customer 3 this shows as 55.561 as most frequent pricepaid by sum quantity from dec-18 through Nov-19
same customer shows 528 as most frequent price paid by sum of quantity from Jan-18 through Nov-18.
so using the above logic to find price paid in last 12 months vs the same figure the 12 months previous
any help would be great thank you and hope this makes sense