@H_
301_0@Public Class LinqToList
'LINQ在C#中使用比较方便，但是在VB中使用比较麻烦，复杂，和C#
用法并不太一样
Dim listNew As List(Of Product) = New List(Of Product) '新商品
Dim listOld As List(Of Product) = New List(Of Product) '旧商品
'****** 给 listNew 加载数据 此处省略******
'****** 给 listOld 加载数据 此处省略******
'
查询 listNew 中的最高价 price1，并按 price，name，unit，model，node分组
Dim temp = From Item In listNew
Group Item By Key = New With {Key Item.Name,Key Item.Unit,Key Item.Model}
Into g = Group Select New With {.price1 = (Aggregate p In g Into Average(p.Price)),.price = (From p In g Select p.Price),.name = Key.Name,.unit = Key.Unit,.model = Key.Model,.note = (From p In g Select p.Note)} 'note并未在分组中，无法再key中
获取
'合并listNew 和listOld ，并按 price，name，unit，model，node分组，求出合并后的最高价price1,相同产品的个数.count
Dim tempMax = From Item In
((From Contact In listNew).Union(From Shipment In listOld))
Group Item By Key = New With {Key Item.Name,Key Item.Model}
Into g = Group Select New With {.price1 = (Aggregate p In g Into Max(p.Price)),.note = (From p In g Select p.Note),.count = g.Count()}
'最低价 .price1 = (Aggregate p In g Into Max(p.Price)) 改成 .price1 = (Aggregate p In g Into Min(p.Price))
'平均价 .price1 = (Aggregate p In g Into Max(p.Price)) 改成 .price1 = (Aggregate p In g Into Average(p.Price))
End Class
Public Class Product
Private mPrice As Double '价格
Private mName As String '
名称
Private mUnit As String '单位
Private mModel As String '规格
Private mNote As String '备注
Public Property Price() As Double '价格
Get
Return mPrice
End Get
Set(ByVal value As Double)
mPrice = value
End Set
End Property
Public Property Name() As String '
名称
Get
Return mName
End Get
Set(ByVal value As String)
mName = value
End Set
End Property
Public Property Unit() As String '单位
Get
Return mUnit
End Get
Set(ByVal value As String)
mUnit = value
End Set
End Property
Public Property Model() As String '规格
Get
Return mModel
End Get
Set(ByVal value As String)
mModel = value
End Set
End Property
Public Property Note() As String '备注
Get
Return mNote
End Get
Set(ByVal value As String)
mNote = value
End Set
End Property
End Class
原文链接：https://www.f2er.com/vb/258753.html
