It sound reasonable but why would you need it. Why to create an extra entity when those 2 can keep what you really need?
Joined: Apr 28, 2008
I was thinking that the 'ownership relationship' was not really property of the item, or the order item. I.e. a distinct ownership entity would be suitable to bridge orders with some order items - even if an order item can belong to at most one order.
I could have an attribute in 'order item' entity along the lines of 'who owns me' - but I didn't know if this was in the spirit of ERD modelling...since ownership is not a property of the 'thing' - it's a type of relationship