circular dependency in entity framework

Is it possible to save model which has got circular dependency ?

I denormalized my Database:

User
--------
UserId
UserName
LastOrder   - fk to last order


Order
-------
OrderId
OrderName
UserId
OrderDate

Is it possible to save sth like this using entityFramework?

what should I change to make it work cause now 开发者_如何学JAVAI have got error:

Unable to determine a valid ordering for dependent operations. Dependencies may exist due to foreign key constraints, model requirements, or store-generated values.

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I had a table that had a relationship to itself and i was getting the same error. Turns out the foreign key has to be nullable. Same table relationship in Entity Framework I hope this saves someone more time than I wasted.