主题：[求助]生成订单号

For Each dr As DataRow In DataTables("采购订单统计").Select("")
    Dim d As Date = dr("需求日期")
    Dim bh As String = dr("供应商") & "-" & Format(d,"yyyyMMdd") & "-" '生成编号的前缀
    Dim max As String
    Dim idx As Integer
    Dim flt As String
    flt = "供应商 = '"& dr("供应商") & "' And 需求日期 >= #" & d & "# And 需求日期 < #" & d.AddDays(1) & "# And [_Identify] <> " & dr("_Identify")
    max = dr.DataTable.Compute("Max(单据编号)",flt)
    If max > "" Then '如果存在最大单据编号
        idx = CInt(max.Substring(bh.length,4)) + 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
    dr("单据编号") = bh & Format(idx,"0000")
Next