linq查询程序：

var query = from c in _CategoryRespository.Table 

where !c.IsDel  c.CategoryToken == token
orderby c.SeqTime descending
select c;

通过sqlserver profiler看到生成的sql语句：

exec sp_executesql N'SELECT TOP (1)
[Project1].[Id] AS [Id],   

····中间字段省略···
[Project1].[DelMan] AS [DelMan]
FROM ( SELECT
[Extent1].[Id] AS [Id],   

····中间字段省略···
[Extent1].[DelMan] AS [DelMan]
FROM [dbo].[Category] AS [Extent1]
WHERE ([Extent1].[IsDel] <> 1) AND (@p__linq__0 = 1 OR [Extent1].[Enabled] = 1) AND (([Extent1].[CategoryToken] = @p__linq__1) OR (([Extent1].[CategoryToken] IS NULL) AND (@p__linq__1 IS NULL)))
) AS [Project1]
ORDER BY [Project1].[SeqTime] DESC',N'@p__linq__0 bit,@p__linq__1 nvarchar(4000)',@p__linq__0=0,@p__linq__1=N'luyouqi'

总体来说就是生成了嵌套。我猜entity这么生成的意义是对于大表，先筛选，然后再排序来提高速度。可是我在本机测试用不嵌套的直接查询的语句，速度更快啊。而且我认为sqlserver等DB对于这样的筛选、排序的语句，肯定也会先（筛选，然后排序）的吧？Entity这么做是不是多余了？

速度比较的截图：