tSQL, EF: SQL from IQueryable<T>.Join()

EFJoin.sql

SELECT 
[Project5].[OrderStatusID] AS [OrderStatusID], 
[Project5].[OrderId] AS [OrderId], 
[Project5].[OrderNumber] AS [OrderNumber], 
[Project5].[PONumber] AS [PONumber], 
[Project5].[DepartmentName] AS [DepartmentName], 
[Project5].[CustomerName] AS [CustomerName], 
[Project5].[CreatedDt] AS [CreatedDt], 
[Project5].[PriorityFl] AS [PriorityFl], 
[Project5].[StatusDescription] AS [StatusDescription], 
[Project5].[CreatedBy] AS [CreatedBy], 
[Project5].[C1] AS [C1]
FROM ( SELECT 
	[Extent1].[OrderId] AS [OrderId], 
	[Extent1].[OrderNumber] AS [OrderNumber], 
	[Extent1].[PONumber] AS [PONumber], 
	[Extent1].[OrderStatusID] AS [OrderStatusID], 
	[Extent1].[CustomerName] AS [CustomerName], 
	[Extent1].[PriorityFl] AS [PriorityFl], 
	[Extent1].[CreatedBy] AS [CreatedBy], 
	[Extent1].[CreatedDt] AS [CreatedDt], 
	[Extent2].[DepartmentName] AS [DepartmentName], 
	[Extent3].[StatusDescription] AS [StatusDescription], 
	(SELECT 
		SUM([Extent9].[TotalAmount]) AS [A1]
		FROM [dbo].[OrderDetail] AS [Extent9]
		WHERE [Extent1].[OrderId] = [Extent9].[OrderID]) AS [C1]
	FROM    [dbo].[OrderHeader] AS [Extent1]
	INNER JOIN [dbo].[Department] AS [Extent2] ON [Extent1].[DepartmentID] = [Extent2].[DepartmentID]
	INNER JOIN [dbo].[OrderStatus] AS [Extent3] ON [Extent1].[OrderStatusID] = [Extent3].[OrderStatusId]
	INNER JOIN [dbo].[OrderDetail] AS [Extent4] ON [Extent1].[OrderId] = [Extent4].[OrderID]
	WHERE ('R' = [Extent1].[RequisitionType]) AND ( EXISTS (SELECT 
		1 AS [C1]
		FROM [dbo].[OrderStatus] AS [Extent5]
		WHERE [Extent5].[OrderStatusId] = [Extent1].[OrderStatusID]
	)) AND ( NOT EXISTS (SELECT 
		1 AS [C1]
		FROM [dbo].[OrderDetail] AS [Extent6]
		WHERE ('R' = [Extent6].[BusinessType]) AND ([Extent6].[OrderID] = [Extent1].[OrderId])
	)) AND (0 = [Extent1].[IsRentalParent]) AND ( NOT EXISTS (SELECT 
		1 AS [C1]
		FROM [dbo].[OrderHeader] AS [Extent7]
		WHERE (0 = [Extent7].[IsRentalParent]) AND ( EXISTS (SELECT 
			1 AS [C1]
			FROM [dbo].[OrderHeader] AS [Extent8]
			WHERE (1 = [Extent8].[IsRentalParent]) AND ([Extent8].[OrderId] = [Extent7].[ParentOrderId])
		)) AND ([Extent7].[OrderId] = [Extent1].[OrderId])
	))
)  AS [Project5]
ORDER BY [Project5].[OrderId] DESC