从SQL GROUP语句中执行实体框架中的组查询

Question

我正在用VB.NET和ASP.NET编写一个发票系统，使用实体框架来存储我的对象。我想总结所有的帐单线项目的任何一个具体的月份，并将它们整理成发票。下面的SQL查询实现了这一点，但是我无法让它在实体框架代码中工作-首先：

SQL查询：

SELECT DISTINCT 
    [database].[dbo].[WorkOrderDetails].PriceCodeID,
    [database].[dbo].[WorkOrderDetails].[Description],
    SUM([database].[dbo].[WorkOrderDetails].[Quantity]) AS [Quantity],
    SUM([Subtotal]) AS Subtotal,
    SUM([Total]) AS Total
FROM 
    [database].[dbo].[WorkOrderDetails] 
INNER JOIN 
    [database].[dbo].[WorkOrders] ON [database].[dbo].[WorkOrderDetails].[WorkOrderID] = [database].[dbo].[WorkOrders].[WorkOrderID]
WHERE 
    [ClientID] = 182 
    AND [WorkOrders].[Date] >= '10/1/2016' 
    AND [WorkOrders].[Date] < '10/31/2016' 
GROUP BY 
    [PriceCodeID], [Description]

此查询的输出类似于以下内容：

PriceCodeID | Description | Quantity | Subtotal | Total  
------------+-------------+----------+----------+--------
26            BOX REFILE        19         47.50    47.50
28            BOX RETRIEVAL     15         37.50    37.50
98            Del/Pu Out       376        545.20   545.20
95            Shredding      16893        760.19   760.19

我的目标是：

• WorkOrder：WorkOrderID，Date，ClientID (外键)，List ( WorkOrderDetail)
• WorkOrderDetail：WorkOrderDetailID，PriceCodeID (外键)，描述，UnitPrice，数量，小计，税收，总计，WorkOrderID (外键)
• PriceCode：PriceCodeID，ShortCode，Description，UnitPrice，Tax

我试图使用下面的语句，但我不确定如何使用GroupBy语句。

newInvoice.Details = _db.WorkOrderDetails
                        .Include("WorkOrder")
                        .Where(Function(wod) wod.WorkOrder.Date >= newInvoice.StartDate And 
                                             wod.WorkOrder.Date < newInvoice.EndDate And 
                                             wod.WorkOrder.ClientID = newInvoice.ClientID)
                        .GroupBy(...)
                        .ToList()

Answer 1

您可以通过以下方法获得聚合结果

Dim aggregate = From wod in _db.WorkOrderDetails
                Where wod.WorkOrder.Date >= newInvoice.StartDate And 
                      wod.WorkOrder.Date < newInvoice.EndDate And 
                      wod.WorkOrder.ClientID = newInvoice.ClientID)
                Group wod By Key = New With { Key wod.PriceCodeID, Key Description }
                Into Group
                Select agg = Key.PriceCodeID,
                             Key.Description,
                             Quantity = Group.Sum(Function(wod) wod.Quantity),
                             Subtotal = Group.Sum(Function(wod) wod.Subtotal),
                             Total = Group.Sum(Function(wod) wod.Total)

您不能在此查询中直接创建新的WorkOrderDetail，因为EF不允许在LINQ查询中创建新的实体类型。但是您可以使用aggregate.AsEnumerable()继续：

newInvoice.Details = aggregate.AsEnumerable()
                     .Select(Function (wod) New WorkOrderDetail ...)