¿Cómo hacer un SQL "Donde existe" en LINQ to Entities?

Question

que realmente quieren hacer algo como esto:

Select * 
from A join B on A.key = B.key join C on B.key = C.key -- propagated keys 
where exists (select null from B where A.key = B.key and B.Name = "Joe") and 
     exists (select null from C where B.key = C.key and C.Name = "Kim") 

¿Cómo sería la declaración de LINQ parecerse utilizando Entity Framework 4 y C#?

Actualización:

Al parecer .Contains() producirá "en los que existe" resultados. Por lo tanto, otro intento
(no sé si esto va incluso compilar LOL):

var inner1 = from recordB in B 
      where recordB.Name = "Joe" 
      select recordB.key; 

var inner2 = from recordC in C 
      where recordC.Name = "Kim" 
      select recordC.key; 

var result = from recordA in A 
      where inner1.Contains(recordA.key) && 
        inner2.Contains(recordA.key) 
      select recordA; 

EDIT: WOW esto es lo que efectivamente trabajadas:

var result = from A in Products 
      where A.kfield1 == 1 && A.kfield2 == 2 && 
        (from B in Btable 
        where B.otherid == "Joe" && // field I want to select by 
          B.kfield1 == A.kfield1 &&  
          B.kfield2 == A.kfield2 // Can keep adding keys here 
        select A.identifier // unique identity field 
        ).Contains(A.identifier) && 
        (from C in Ctable 
        where C.otherid == "Kim" && // field I want to select by 
          C.kfield1 == A.kfield1 &&  
          C.kfield2 == A.kfield2 // Can keep adding keys here 
        select A.identifier // unique identity field 
        ).Contains(A.identifier) 
      select A; 

Esto produjo este SQL:

SELECT [t0].[identifier], [t0].* 
FROM [A] AS [t0] 
WHERE ([t0].[kfield1] = @p0) AND ([t0].[kfield2] = @p1) AND (EXISTS(
    SELECT NULL AS [EMPTY] 
    FROM [B] AS [t1] 
    WHERE ([t0].[identifier] = [t0].[identifier]) AND ([t1].[otherid] = @p2) AND 
      ([t1].[kfield1] = [t0].[kfield1]) AND 
      ([t1].[kfield2] = [t0].[kfield2]))) AND (EXISTS(
    SELECT NULL AS [EMPTY] 
    FROM [C] AS [t2] 
    WHERE ([t0].[identifier] = [t0].[identifier]) AND ([t2].[otherid] = @p3) AND 
      ([t2].[kfield1] = [t0].[kfield1]) AND 
      ([t2].[kfiekd2] = [t0].[kfield2]))) 

Que es lo que yo quería. Observe el [t0]. [Identificador] = [t0]. [Identificador], que filtra los valores nulos porque null no se compara con nada incluido él mismo (en SQL)

Answer 1

El método de extensión .Any() normalmente se asigna a exists.

Answer 2

Ha intentado agregar su acondicionador exists a tus uniones?

from a in context.AEntity 
Join B in context.BEntity on A.Key equals B.Key && B.Name == "Joe" 
Join C in context.CEntity on B.Key equals C.Key && C.Name == "Kim"; 

No estoy seguro si eso funcionará, pero vale la pena intentarlo.