Linq join on 多条件

  var a = from m in DbContext.Set<T1>()
                    join q in DbContext.Set<T2>() 
                    on  new { m.ID, Phone=m.Phone1 } equals new { q.ID, Phone=q.Phone2 }
                    where m.Phone1 !=null
                    select new { m.ID, m.Phone1 };
            a = a.OrderBy(m => m.Phone1).Skip(2).Take(2);

SELECT 
            [Extent1].[ID] AS [ID], 
            [Extent1].[Phone1] AS [Phone1], 
            1 AS [C1]
            FROM  [dbo].[T1] AS [Extent1]
            INNER JOIN [dbo].[T2] AS [Extent2] ON ([Extent1].[ID] = [Extent2].[ID]) AND (([Extent1].[Phone1] = [Extent2].[Phone2]) OR (([Extent1].[Phone1] IS NULL) AND ([Extent2].[Phone2] IS NULL)))
            WHERE [Extent1].[Phone1] IS NOT NULL
       

所以linq为什么要这么写，看到生成的sql语句 就不言而喻了，因为linq多管闲事的将NULL给总结进去了