IQueryable 丢失 ORDER BY答案

【问题标题】：IQueryable losing the ORDER BYIQueryable 丢失 ORDER BY
【发布时间】：2015-07-20 15:18:05
【问题描述】：

谁能解释为什么会这样？

Dim lReturn As IQueryable(Of Inventory) = context.Inventories.OrderBy(Function(o) o.SortOrder)

'' --- In the sql profiler, I can see Order by is added
'' Dim lst = lReturn.ToList 

If Not loggedInUser.IsAdmin Then
    lReturn = lReturn.Where(Function(x) x.AdminOnly = False)
    '' --- In the sql profiler, I can see Order by is added
    '' Dim lst = lReturn.ToList 

    lReturn = From f In lReturn
              Group Join a In context.AssignServices On f.ID Equals a.Id Into fas = Group
              From a In fas.Where(Function(x) x.AgentId = loggedInUser.CompanyId).DefaultIfEmpty()
              Where a.Assign = True OrElse f.isVisibleToAllAgents = True
              Select f
    '' --- In the sql profiler, I can see **Order by is not included**
    Dim lst = lReturn.ToList     ''*Problem is here*

End If

lReturn 在开头已经包含了 Order By，这是一个 Lambda 表达式。如果用户不是管理员，则最后一个 Linq 查询由于某种原因不包括 order by。我正在使用 sql profiler 来找出查询的外观，如下所示

exec sp_executesql N'SELECT 
[Extent1].[ID] AS [ID], 
[Extent1].[Name] AS [Name], 
.........
[Extent1].[SortOrder] AS [SortOrder]
FROM  [dbo].[Inventories] AS [Extent1]
LEFT OUTER JOIN [dbo].[AssignService] AS [Extent2] ON ([Extent1].[ID] = [Extent2].[Id]) AND ([Extent2].[AgentId] = @p__linq__0)
WHERE (0 = [Extent1].[AdminOnly]) AND ([Extent2].[Assign] = 1 OR [Extent1].[isVisibleToAllAgents] = 1) ,N'@p__linq__0 int',@p__linq__0=112

这是一种常规行为吗？还是我错过了什么？

【问题讨论】：

标签： vb.net linq lambda sql-server-profiler

【解决方案1】：

基于 LINQ 的 ORM 对支持哪些特定的 order by 模式已经放宽了规则。始终支持的（根据我的经验）是在查询结束时排序，后面只有 Where 和 Select 操作。

可能 order by 在连接处丢失。我一点都不惊讶。

【讨论】：