为什么实体框架在生成SQL时忽略Take（）方法？

Question

我在实体框架中使用.Skip和.Take方法。 .Skip调用在生成SQL时正在使用。这个.Take不是。此代码：

 public IList<DocPullRun> GetDocRunsPaginated(int startRowIndex, int maximumRows) { 

     Logger.Debug("GetDocRunsPaginated: startRowIndex: {0}, maximumRows: {1}", startRowIndex, maximumRows); 
     Debug.Assert(startRowIndex >= 0); 
     IOrderedQueryable<DocPullRun> sortedPulls = 
      from run in DB.DocPullRuns 
       .Include("DocumentPullDefinition") 
       .Include("DocumentPullDefinition.Case") 
       .Include("DocumentPullDefinition.DocCategory") 
       .Include("DocumentPullDefinition.Repository") 
       .Include("DocumentPullDefinition.Repository.ConcordanceRepository") 

      orderby run.PullStarted descending 
      select run; 

     IQueryable<DocPullRun> query = sortedPulls.Skip(startRowIndex); 
     if (maximumRows > 0) 
      query.Take(maximumRows); 

     return query.ToList(); 
    } 

结果列在下面所示的本SQL（注意，在这种呼叫，startRowIndex是0和maximumRows是）。 Where子句包含WHERE [Project1]。[row_number]> 0（即.Skip部分），但我期望看到一个选择TOP 10，但是只是看到Select。结果列表中有超过10个元素。请注意，我运行SQL跟踪并查看SQL确实被延迟，直到最后一行才发送：query.ToList（）。这是一些类型的错误？

SELECT 
[Project1].[C1] AS [C1], 
[Project1].[Id] AS [Id], 
[Project1].[PullStarted] AS [PullStarted], 
[Project1].[PullEnded] AS [PullEnded], 
[Project1].[MatchedQuery] AS [MatchedQuery], 
[Project1].[NewDocs] AS [NewDocs], 
[Project1].[UpdatedDocs] AS [UpdatedDocs], 
[Project1].[DeletedDocs] AS [DeletedDocs], 
[Project1].[Errors] AS [Errors], 
[Project1].[C2] AS [C2], 
[Project1].[Id1] AS [Id1], 
[Project1].[Requestor] AS [Requestor], 
[Project1].[RequestTime] AS [RequestTime], 
[Project1].[Query] AS [Query], 
[Project1].[Enabled] AS [Enabled], 
[Project1].[LastPullTime] AS [LastPullTime], 
[Project1].[Case_ID] AS [Case_ID], 
[Project1].[Case_Name] AS [Case_Name], 
[Project1].[Client_ID] AS [Client_ID], 
[Project1].[Matter_ID] AS [Matter_ID], 
[Project1].[Is_Active] AS [Is_Active], 
[Project1].[Requires_Case_Specific_Permissions] AS [Requires_Case_Specific_Permissions], 
[Project1].[Last_Update] AS [Last_Update], 
[Project1].[C3] AS [C3], 
[Project1].[Category_ID] AS [Category_ID], 
[Project1].[CategoryName] AS [CategoryName], 
[Project1].[DefaultGridLayout] AS [DefaultGridLayout], 
[Project1].[C4] AS [C4], 
[Project1].[Repository_ID] AS [Repository_ID], 
[Project1].[Description] AS [Description], 
[Project1].[OfficeAbbr] AS [OfficeAbbr], 
[Project1].[C5] AS [C5], 
[Project1].[Repository_ID1] AS [Repository_ID1], 
[Project1].[ConcordanceDBId] AS [ConcordanceDBId], 
[Project1].[Repository_ID2] AS [Repository_ID2], 
[Project1].[RepositoryType_Id] AS [RepositoryType_Id] 
FROM (SELECT [Project1].[Id] AS [Id], [Project1].[PullStarted] AS [PullStarted], [Project1].[PullEnded] AS [PullEnded], [Project1].[MatchedQuery] AS [MatchedQuery], [Project1].[NewDocs] AS [NewDocs], [Project1].[UpdatedDocs] AS [UpdatedDocs], [Project1].[DeletedDocs] AS [DeletedDocs], [Project1].[Errors] AS [Errors], [Project1].[Id1] AS [Id1], [Project1].[Requestor] AS [Requestor], [Project1].[RequestTime] AS [RequestTime], [Project1].[Query] AS [Query], [Project1].[Enabled] AS [Enabled], [Project1].[LastPullTime] AS [LastPullTime], [Project1].[Case_ID] AS [Case_ID], [Project1].[Case_Name] AS [Case_Name], [Project1].[Client_ID] AS [Client_ID], [Project1].[Matter_ID] AS [Matter_ID], [Project1].[Is_Active] AS [Is_Active], [Project1].[Requires_Case_Specific_Permissions] AS [Requires_Case_Specific_Permissions], [Project1].[Last_Update] AS [Last_Update], [Project1].[Category_ID] AS [Category_ID], [Project1].[CategoryName] AS [CategoryName], [Project1].[DefaultGridLayout] AS [DefaultGridLayout], [Project1].[Repository_ID] AS [Repository_ID], [Project1].[Description] AS [Description], [Project1].[OfficeAbbr] AS [OfficeAbbr], [Project1].[Repository_ID1] AS [Repository_ID1], [Project1].[ConcordanceDBId] AS [ConcordanceDBId], [Project1].[Repository_ID2] AS [Repository_ID2], [Project1].[RepositoryType_Id] AS [RepositoryType_Id], [Project1].[C1] AS [C1], [Project1].[C2] AS [C2], [Project1].[C3] AS [C3], [Project1].[C4] AS [C4], [Project1].[C5] AS [C5], row_number() OVER (ORDER BY [Project1].[PullStarted] DESC) AS [row_number] 
    FROM (SELECT 
     [Extent1].[Id] AS [Id], 
     [Extent1].[PullStarted] AS [PullStarted], 
     [Extent1].[PullEnded] AS [PullEnded], 
     [Extent1].[MatchedQuery] AS [MatchedQuery], 
     [Extent1].[NewDocs] AS [NewDocs], 
     [Extent1].[UpdatedDocs] AS [UpdatedDocs], 
     [Extent1].[DeletedDocs] AS [DeletedDocs], 
     [Extent1].[Errors] AS [Errors], 
     [Extent2].[Id] AS [Id1], 
     [Extent2].[Requestor] AS [Requestor], 
     [Extent2].[RequestTime] AS [RequestTime], 
     [Extent2].[Query] AS [Query], 
     [Extent2].[Enabled] AS [Enabled], 
     [Extent2].[LastPullTime] AS [LastPullTime], 
     [Extent3].[Case_ID] AS [Case_ID], 
     [Extent3].[Case_Name] AS [Case_Name], 
     [Extent3].[Client_ID] AS [Client_ID], 
     [Extent3].[Matter_ID] AS [Matter_ID], 
     [Extent3].[Is_Active] AS [Is_Active], 
     [Extent3].[Requires_Case_Specific_Permissions] AS [Requires_Case_Specific_Permissions], 
     [Extent3].[Last_Update] AS [Last_Update], 
     [Extent4].[Category_ID] AS [Category_ID], 
     [Extent4].[CategoryName] AS [CategoryName], 
     [Extent5].[DefaultGridLayout] AS [DefaultGridLayout], 
     [Extent6].[Repository_ID] AS [Repository_ID], 
     [Extent6].[Description] AS [Description], 
     [Extent6].[OfficeAbbr] AS [OfficeAbbr], 
     [Extent9].[Repository_ID] AS [Repository_ID1], 
     [Extent9].[ConcordanceDBId] AS [ConcordanceDBId], 
     [Extent12].[Repository_ID] AS [Repository_ID2], 
     [Extent13].[RepositoryType_Id] AS [RepositoryType_Id], 
     1 AS [C1], 
     1 AS [C2], 
     1 AS [C3], 
     1 AS [C4], 
     1 AS [C5] 
     FROM   [dbo].[DocPullRuns] AS [Extent1] 
     LEFT OUTER JOIN [dbo].[DocumentPullDefinitions] AS [Extent2] ON [Extent1].[DocumentPullDefinitionId] = [Extent2].[Id] 
     LEFT OUTER JOIN [dbo].[Cases] AS [Extent3] ON [Extent2].[CaseId] = [Extent3].[Case_ID] 
     LEFT OUTER JOIN [dbo].[DocCategories] AS [Extent4] ON [Extent2].[CategoryId] = [Extent4].[Category_ID] 
     LEFT OUTER JOIN [dbo].[DocCategories] AS [Extent5] ON [Extent2].[CategoryId] = [Extent5].[Category_ID] 
     LEFT OUTER JOIN [dbo].[Repositories] AS [Extent6] ON [Extent2].[RepositoryId] = [Extent6].[Repository_ID] 
     LEFT OUTER JOIN (SELECT [Extent7].[Repository_ID] AS [Repository_ID3], [Extent7].[RepositoryType_Id] AS [RepositoryType_Id], [Extent7].[Description] AS [Description], [Extent7].[OfficeAbbr] AS [OfficeAbbr], [Extent8].[Repository_ID] AS [Repository_ID4], [Extent8].[ConcordanceDBId] AS [ConcordanceDBId] 
      FROM [dbo].[Repositories] AS [Extent7] 
      LEFT OUTER JOIN [dbo].[ConcordanceRepositories] AS [Extent8] ON [Extent7].[Repository_ID] = [Extent8].[Repository_ID]) AS [Join6] ON [Extent2].[RepositoryId] = [Join6].[Repository_ID3] 
     LEFT OUTER JOIN [dbo].[ConcordanceRepositories] AS [Extent9] ON [Join6].[Repository_ID4] = [Extent9].[Repository_ID] 
     LEFT OUTER JOIN (SELECT [Extent10].[Repository_ID] AS [Repository_ID5], [Extent10].[RepositoryType_Id] AS [RepositoryType_Id], [Extent10].[Description] AS [Description], [Extent10].[OfficeAbbr] AS [OfficeAbbr], [Extent11].[Repository_ID] AS [Repository_ID6], [Extent11].[ConcordanceDBId] AS [ConcordanceDBId] 
      FROM [dbo].[Repositories] AS [Extent10] 
      LEFT OUTER JOIN [dbo].[ConcordanceRepositories] AS [Extent11] ON [Extent10].[Repository_ID] = [Extent11].[Repository_ID]) AS [Join9] ON [Extent2].[RepositoryId] = [Join9].[Repository_ID5] 
     LEFT OUTER JOIN [dbo].[ConcordanceRepositories] AS [Extent12] ON [Join9].[Repository_ID6] = [Extent12].[Repository_ID] 
     LEFT OUTER JOIN [dbo].[Repositories] AS [Extent13] ON [Extent2].[RepositoryId] = [Extent13].[Repository_ID] 
    ) AS [Project1] 
) AS [Project1] 
WHERE [Project1].[row_number] > 0 
ORDER BY [Project1].[PullStarted] DESC 

Answer 1

query.Take（）不改变查询;而是返回代码忽略的新的表达式。因此，将您的代码更改为：

if (maximumRows > 0) 
    query = query.Take(maximumRows); 

Answer 2

如果您只想要最大行数，则不需要if语句。如果它没有达到最大值，那么它只会返回所得到的值。

你可以只说：

return query.Take(maximumRows).ToList();