小编ghi*_*gad的帖子

我一直在使用一些LINQ over Entities,我得到了奇怪的结果,我想得到解释......

给出以下LINQ查询,

// Sample # 1
IEnumerable<GroupInformation> groupingInfo;
groupingInfo = from a in context.AccountingTransaction
               group a by a.Type into grp
               select new GroupInformation()
               {
                   GroupName = grp.Key,
                   GroupCount = grp.Count()
               };

我得到以下SQL查询(取自SQL Profiler):

SELECT 
    1 AS [C1], 
    [GroupBy1].[K1] AS [Type], 
    [GroupBy1].[A1] AS [C2]
    FROM ( SELECT 
        [Extent1].[Type] AS [K1], 
        COUNT(1) AS [A1]
        FROM [dbo].[AccountingTransaction] AS [Extent1]
        GROUP BY [Extent1].[Type]
    )  AS [GroupBy1]

到现在为止还挺好.

如果我将我的LINQ查询更改为:

// Sample # 2
groupingInfo = context.AccountingTransaction.
                 GroupBy(a => a.Type).
                 Select(grp => new GroupInformation() …