主题：[求助]

没看懂你要做什么，请具体说明你要做到的效果

        Dim drs As List(of DataRow)
        Dim Filter As String
        Dim d1 As Date = e.DataRow("付款日期")
        d1 = new Date(d1.Year, d1.Month, 1)
        Dim d2 As Date = d1.AddMonths(1)
        Filter = "[付款日期] >= #" & d1 & "# and 付款日期 < #" & d2 & "# And [户名] = '" & e.DataRow("户名") & "'"
        drs = e.DataTable.Select(Filter)
        For Each dr As DataRow In drs
            Filter = "[付款日期] <= #" & e.DataRow("付款日期") & "# and 付款日期 >= #" & d1 & "# And [户名] = '" & e.DataRow("户名") & "'"
            Dim Val1 As Double = e.DataTable.Compute("Sum(实付金额)",Filter)
            dr("实付金额") = Val1
        Next

加一列【累计实付金额】，然后显示累计结果，如

       Dim drs As List(of DataRow)
        Dim Filter As String
        Dim d1 As Date = e.DataRow("付款日期")
        d1 = new Date(d1.Year, d1.Month, 1)
        Dim d2 As Date = d1.AddMonths(1)
        Filter = "[付款日期] >= #" & d1 & "# and 付款日期 < #" & d2 & "# And [户名] = '" & e.DataRow("户名") & "'"
        drs = e.DataTable.Select(Filter, "付款日期,_sortkey")
        For Each dr As DataRow In drs
            Filter = "[付款日期] <= #" & e.DataRow("付款日期") & "# and 付款日期 >= #" & d1 & "# And [户名] = '" & e.DataRow("户名") & "'"
            Dim Val1 As Double = e.DataTable.Compute("Sum(实付金额)",Filter)
            dr("累计实付金额") = Val1
        Next