Question

I have 2 tables that I import to EF model.
First table has a property [section] that acts as foreign key to the second table.
When I map this property in model to the table and try to compile I get this error:

Problem in Mapping Fragments starting
at lines 158, 174: Non-Primary-Key
column(s) [Section] are being mapped
in both fragments to different
conceptual side properties – data
inconsistency is possible because the
corresponding conceptual side
properties can be independently
modified.

If i remove this property from the model it passes, but when I query the data I don’t have the section field.

I know that I can get it by using the navigation field and reading this property from the second table, but to make it work I must include the other table in my query.

var res  = from name in Context.Table1.Include("Table2")...

Why do I need to include the association just for one field?

UPDATE
To make it more clear:

Table 1 has fields:
ItemId – key
section – foreign key
title

Table 2 has fields:
SectionId – key
Name

When I set the associations the section property from the first table must be removed.

Answer 1

In EF 4 you can use FK associations for this.

In EF 1 the easiest way to get one field from a related table is to project:

var q = from t1 in Context.Table1
        where //...
        select new 
        {
            T1 = t1,
            Section = t1.Section.SectionId
        };
var section = q.First().Section;

If it’s a key property, you can get the value via the EntityKey:

var t1 = GetT1();
var section = (int)t1.SectionReference.EntityKey.Values[0].Value;

Generally, I don’t like this last method. It’s too EF-specific, and fails if your query MergeOption is set to NoTracking.