实体框架中的外部连接太多4？ [英] Too Many Left Outer Joins in Entity Framework 4?

问题描述

我有一个产品实体，它有0或1个BestSeller实体。由于某些原因，我说：

  db.Products.OrderBy（p => p.BestSeller.rating）.ToList（ ）; 
  

我得到的SQL有一个额外外连接（下面）。如果我添加第二个0或1关系船，并且由两者订购，那么我将获得外连接。似乎每个这样的实体都生产2个外连接而不是一个。 LINQ to SQL的行为与您预期的完全一样，没有额外的加入。

有没有人经历过这个，或者知道如何解决它？

  SELECT 
 [Extent1]。[id] AS [id]，
 [Extent1]。[ProductName] AS [ProductName] 
 FROM [dbo]。[产品] AS [Extent1] 
 LEFT OUTER JOIN [dbo]。[BestSeller] AS [Extent2] ON [Extent1]。[id] = [Extent2]。[id] 
 LEFT OUTER JOIN [dbo]。[BestSeller] AS [Extent3] ON [Extent2]。[id] = [Extent3]。[id] 
 ORDER BY [Extent3]。[rating] ASC 
  

解决方案

我问Julie Lerman在这里回答了一个类似的问题： p>

请参阅简单Linq查询对同一表格重复加入？

I have a product entity, which has 0 or 1 "BestSeller" entities. For some reason when I say:

db.Products.OrderBy(p => p.BestSeller.rating).ToList();

the SQL I get has an "extra" outer join (below). And if I add on a second 0 or 1 relation ship, and order by both, then I get 4 outer joins. It seems like each such entity is producing 2 outer joins rather than one. LINQ to SQL behaves exactly as you'd expect, with no extra join.

Has anyone else experienced this, or know how to fix it?

SELECT 
[Extent1].[id] AS [id], 
[Extent1].[ProductName] AS [ProductName]
FROM   [dbo].[Products] AS [Extent1]
LEFT OUTER JOIN [dbo].[BestSeller] AS [Extent2] ON [Extent1].[id] = [Extent2].[id]
LEFT OUTER JOIN [dbo].[BestSeller] AS [Extent3] ON [Extent2].[id] = [Extent3].[id]
ORDER BY [Extent3].[rating] ASC

解决方案

I asked Julie Lerman to answer a similar question here:

Please see Simple Linq query has duplicated join against same table?

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