[EDITED: I left the original question below, with some more context and code to reproduce the problem. The short version below contains the essence of the question]
Shor
Does this work?
Dim a = From p In products Join o In orders On p.Id Equals o.ProductId
Order By p.DateCreated
Select New With {.id = p.Id, .OrderDate = o.OrderDate, .CustomerId = o.CustomerId, .DateCreated = p.DateCreated}
Dim b = From outerOrder In orders _
Where outerOrder.OrderDate = currentDate _
AndAlso outerOrder.ProductId = _
(From x In a Where x.OrderDate = outerOrder.OrderDate _
AndAlso x.CustomerId = outerOrder.CustomerId _
Select x.id).FirstOrDefault