Logic-Suppose the customer "A10" has brought its first product "3" in "feb-06".
the second different product "1"was brought on dec-08. show the pattern of the customers when they buy a next new unique product.
Between this time "A10" would have brought again product "3" which is not considered in the buying pattern as it considered to be an upgrade or re-buying.The minimum date pertaining to a unique product would be considered in the buying pattern.
Idea is to see when a particular customer buy a certain product,which is the next unique product that the same customer buy and when.
Buying pattern is related to the new unique products brought by a particular customer.Attached is the dummy workbook.