왜 Linq to Entities는 외부 외부 조인을 생성합니까?

Question

누군가 linq가 엔티티에 항상 왼쪽 외부 조인을 생성하는 것처럼 보이는 이유를 아는 사람이 있는지 궁금합니다. 나는 선택적인 관계에서 그것을 이해할 것이지만 관계가 필수 일 때 그것은 좋은 말이되지 않습니다.

내부 조인을 생성하는 방법을 알고있는 사람이 있습니까? 당신은 내부 만들 수 있습니다

Answer 1

http://blogs.microsoft.co.il/blogs/idof/archive/2008/10/01/entity-framework-generated-queries-look-out.aspx

Answer 2

조인. join 키워드 만 사용하면됩니다.

var query = from od in db.SalesOrderHeader 
      join c in db.Customer on od.Customer.CustomerID equals c.CustomerID 
      select new { c.AccountNumber, od.OrderDate }; 

동등한 SQL :

SELECT 
1 AS [C1], 
[Extent2].[AccountNumber] AS [AccountNumber], 
[Extent1].[SalesOrderID] AS [SalesOrderID], 
[Extent1].[RevisionNumber] AS [RevisionNumber], 
[Extent1].[OrderDate] AS [OrderDate], 
[Extent1].[DueDate] AS [DueDate], 
[Extent1].[ShipDate] AS [ShipDate], 
[Extent1].[Status] AS [Status], 
[Extent1].[OnlineOrderFlag] AS [OnlineOrderFlag], 
[Extent1].[SalesOrderNumber] AS [SalesOrderNumber], 
[Extent1].[PurchaseOrderNumber] AS [PurchaseOrderNumber], 
[Extent1].[AccountNumber] AS [AccountNumber1], 
[Extent1].[CreditCardApprovalCode] AS [CreditCardApprovalCode], 
[Extent1].[SubTotal] AS [SubTotal], 
[Extent1].[TaxAmt] AS [TaxAmt], 
[Extent1].[Freight] AS [Freight], 
[Extent1].[TotalDue] AS [TotalDue], 
[Extent1].[Comment] AS [Comment], 
[Extent1].[rowguid] AS [rowguid], 
[Extent1].[ModifiedDate] AS [ModifiedDate], 
[Extent1].[BillToAddressID] AS [BillToAddressID], 
[Extent1].[ContactID] AS [ContactID], 
[Extent1].[ShipMethodID] AS [ShipMethodID], 
[Extent1].[CreditCardID] AS [CreditCardID], 
[Extent1].[CurrencyRateID] AS [CurrencyRateID], 
[Extent1].[CustomerID] AS [CustomerID], 
[Extent1].[SalesPersonID] AS [SalesPersonID], 
[Extent1].[TerritoryID] AS [TerritoryID] 
FROM [Sales].[SalesOrderHeader] AS [Extent1] 
INNER JOIN [Sales].[Customer] AS [Extent2] ON ([Extent1].[CustomerID] = [Extent2].[CustomerID]) OR (([Extent1].[CustomerID] IS NULL) AND ([Extent2].[CustomerID] IS NULL))