主题：求助订单交付逐减的代码写法

Dim ls As List(Of String) = DataTables("订单明细_张笑南").GetValues("D2C条码")
For Each ary As String In ls
    Dim sumin As Double = DataTables("采购入库明细").compute("sum(采购入库数量)", "条码 = '" & ary & "'")
    Dim drs As List(Of DataRow) = DataTables("订单明细_张笑南").Select("D2C条码 = '" & ary & "'", "_Identify")
    For i As Integer = 0 To drs.count - 1
        Dim dr As DataRow = drs(i)
        Dim sumout As Double = DataTables("订单明细_张笑南").compute("sum(入库数量)", "D2C条码 = '" & dr("D2C条码") & "' and _Identify < " & dr("_Identify"))
        Dim st As Double = sumin - sumout
        If st >= dr("订单数量") Then
            If i = drs.count - 1 Then
                dr("入库数量") = st
                dr("待交货数量") = dr("订单数量") - dr("入库数量")
            Else
                dr("入库数量") = dr("订单数量")
                dr("待交货数量") = 0
            End If
        Else
            dr("入库数量") = iif(st>=0, st, 0)
            dr("待交货数量") = dr("订单数量") - dr("入库数量")
        End If
    Next
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