Linq to Entities cycling left outer joins - sql

Question

I have following problem with Linq to entities.
Diagram:
Linq to entities query (incomplete yet):
from a in Anlaesse
join b in Beurteilung on a.AnlassID equals b.AnlassID into ab
from b in ab.DefaultIfEmpty()
join r in Rangliste on a.AnlassID equals r.AnlassId
join p in Pony on r.PonyId equals p.PonyID into rp
from p in rp.DefaultIfEmpty()
where a.AnlassID == 67
select new
{
BeurteilungId = b.BeurteilungID == null ? 0 : b.BeurteilungID,
PonyID = p.PonyID == null ? 0 : p.PonyID,
Name = p.Name,
PonyName1 = r.PonyName1,
AnlassId = a.AnlassID == null ? 0 : a.AnlassID
}
Generated SQL:
SELECT
[Extent1].[AnlassID] AS [AnlassID],
CASE WHEN ([Extent2].[BeurteilungID] IS NULL) THEN 0 ELSE
[Extent2].[BeurteilungID] END AS [C1],
CASE WHEN ([Extent4].[PonyID] IS NULL) THEN 0 ELSE [Extent4].[PonyID] END
AS [C2],
[Extent4].[Name] AS [Name],
[Extent3].[PonyName1] AS [PonyName1]
FROM [sspv].[Anlaesse] AS [Extent1]
LEFT OUTER JOIN [sspv].[Beurteilung] AS [Extent2] ON [Extent1].[AnlassID]
= [Extent2].[AnlassID]
INNER JOIN [sspv].[Rangliste] AS [Extent3] ON [Extent1].[AnlassID] =
[Extent3].[AnlassId]
LEFT OUTER JOIN [sspv].[Pony] AS [Extent4] ON [Extent3].[PonyId] =
[Extent4].[PonyID]
WHERE 67 = [Extent1].[AnlassID]
Problem is that I'm unable to add the left outer join between Pony and Beurteilung because all tables are already "used" in my query. Without this the result is wrong because it Returns for each Pony all Beurteilung.

Answer 1

Let's assume you want to left join Pony to Beurteilung. And let's assume both have a PonyId property. A clause like this would act as an inner join:
where p.PonyId == b.PonyId
A clause like this would act as a left join.
where b == null || p.PonyId == b.PonyId
However, you are finding this hard because it really doesn't look like you are using Entity Framework properly. Have you mapped any navigation properties or collections? If you haven't then add them because this is sort of the point of EF. If you have then you shouldn't have any need to use inner or left joins; you just traverse the navigation properties.