Linq Mapping Problem with 1 to 0.1 relationships

I have an linq to entity mapping issue. I have three tables.

Table 1 - ItemsB(ID(key), Part_Number(will be null until built), other item b information)

Table 2 - ItemsA(ID(key), Part_Number(will be null until built), other item a information)

Table 3 - WebItems(Item_id, web item information) *Consists of items from both ItemsB and ItemsA after they are built and pushed over to this table.

ItemsA/ItemsB will have a 1 to 0.1 relationship with WebItems. Part_Number maps to Item_id.

I am using EF4.0.

Problem is after i set up the association/mappings as stated above i get an error message stating: "Problem in mapping fragment at lines so and so: Column [Part_Number] are being mapped in both fragments to different conceptual side properties."

Usually i know what to do in this case. Get rid of the property [开发者_JAVA技巧Part_Number]. Problem is i need to access [Part_Number] in both ItemsB and ItemsA quite frequently without going to webitems. Not to mention webitems will not always have the [Part_Number] populated at certain points depending upon whether the items have be pushed to webitems.

Does anyone know how to get around this?

Thanks in advance.

As I understand it ItemA and ItemB to WebItem in one-to-one relation. One-to-one relation in EF always demands that relation is build on primary keys and one side is mandatory (principal) because dependent entity will have primary key and foreign key in one column. Once you assign primary key in dependent entity you must have principal entity with the same primary key otherwise you will violate referential integrity defined by foreign key.

The problem is that your Part_Number is primary key and foreign key in the same time. To allow such mapping in EFv4 you must use Foreign Key association instead of Independent association. Here is brief description how to create foreign key association in the designer. Once you define referential constrain get back to mapping window of association and delete the mapping.