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  1. #1
    Join Date
    Jun 2012

    Question ERD Diagram Many-to-Many Relationship with Restriction

    Hello, I have some homework that I can't seem to figure out. I've tried everything I can think of but I don't think it's right. Here is the problem:

    Donors only have a relationship with an Item entity type. A donor must have donated one or more items, and an item may have no donors, one or more donors.

    What I have is



    It's an obvious many to many relationship and I need an intersection entity but since it states that donors can only have a relationship with the item entity, what do I do?

    I was thinking of having DONORITEM that has both primary keys of the respective entities but it just seems wrong with that restriction.


  2. #2
    Join Date
    Oct 2009
    221B Baker St.
    If your intersection entity has only 2 columns (one for donor, the other for item) you should be fine.

    Why might this not work for you?

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