How to select similar sets in SQL

Question

I have the following tables:

Order
----
ID (pk)

OrderItem
----
OrderID (fk -> Order.ID)
ItemID (fk -> Item.ID)
Quantity

Item
----
ID (pk)
         


        

Answer 1

This is one kind of data mining problem. So instead of using sql you can use Apriori algorithm with 85% support. The implementation of this algorithm is freely available in many tools.