I have a database table 'Sales', with 2 fields Product and Customer. It shows the product purchased by customers. I like to find subsets of this table. Each subset has Product and Customers. Each customer must have purchased all the product in a given subset. It's very trivial to create subsets (Product X Customer) like 1x1 or NPx1 or 1 x NC. (NP = Number of Products, NC = Number of Customers) I am looking forward to find out subsets where NP and NC have higher values. Let's say top 10 values for NP in NP x 2 or NP x 3, or even NP x NC ie.. top 10 values for NP for each of top 10 values of NC.

Pointers, directions, code :-) ?
Thanks..

Update: I am not necessarily looking for SQL solution.

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