Problem in mapping fragments in EF4

I have the following model:

But when i compile with VS2010, i get the following erro开发者_StackOverflowr:

Error 2 Error 3007: Problem in mapping fragments starting at lines 1784, 2018:Column(s) [createdby] are being mapped in both fragments to different conceptual side properties.

What do i want ? Actually i want the Note entity to have FK to User entity. When does the error appear ? When i add the FK User to Note i have the error. If i remove the link, no problem. What is the problem ? Thanks John

I also have a "User" entity (based on a View) and several tables with CreatedByUser and ModifiedByUser references.

This works for me without getting the "must be null" error:

• On the "Note" entity: right-click: “Add > Association...”.
• Select "User" as the right-side "End Entity".
• Swap the multiplicities: "Notes" should be "Many" and "User" should be "One".
• I deselect the right-side Navigation Property, as I'll never navigate from "User" to the other tables: but that's up to you.
• If you have both "CreatedBy" and "ModifiedBy" properties, then you might want to change the Association Name to something more meaningful (e.g. change "NoteUser" to "NoteCreatedByUser"
• Ditto for the Navigation Property (e.g. change "User" to "CreatedByUser")
• Leave “Add foreign key properties....” unchecked.
• Click OK.
• IMPORTANT: in the “Properties” window, go to Referential Constraint and click the ellipsis.
• Select "User" as the Principal.
• Change the Dependent Property to the appropriate value (e.g. "CreatedBy")
• Click OK.

Done!

Screen shots from my project below.

My guess is that the association on the User entity has been defined on Username and Username is a candidate key (has a unique index defined on it) in SQL Server. While you can create a relationship based on this setup in SQL Server, current version of EF does NOT support creating associations based on candidate keys: In EF (3.5 and 4.0) FKs MUST point to Primary Keys.

The only way to make this working is to create a new int field inside Note table (like UserId) and then create a new relationship between User.Id (PK) and Note.UserID (FK) and EF will happily create a association based on that for you.