主题：自动编号跨年

Select e.DataCol.Name
    Case "登记日期","类别"
        If e.DataRow.IsNull("登记日期") OrElse e.DataRow.IsNull("类别") Then
            e.DataRow("编号") = Nothing
        Else
            Dim d As Date = e.DataRow("登记日期")
            Dim y As Integer = d.Year
            Dim bh As String = e.DataRow("类别") & "[" & Format(d,"yyyy") & "]" '生成编号的前缀
            If e.DataRow("编号").StartsWith(bh) = False '如果立案编号前缀不符
                Dim max As String
                Dim idx As Integer
                Dim flt As String
                flt = "类别 = '"& e.DataRow("类别")  & " 'And [_Identify] <> " & e.DataRow("_Identify")
                max = e.DataTable.Compute("Max(编号)",flt) '取得区划机关行为简称的最大单据编号
                If max > "" Then '如果存在最大立案编号
                    idx = CInt(max.Substring(8,3)) + 1 '获得最大单据编号的后四位顺序号,并加1
                Else
                    idx = 1 '否则顺序号等于1
                End If
                e.DataRow("编号") = bh & Format(idx,"000")
            End If
        End If
End Select
老师，这段代码我跨年之后怎么从001自动开始呢？比如2015年？