Select e.DataCol.Name

    Case "开工日期","工程项目简称"

        If e.DataRow.IsNull("开工日期") OrElse e.DataRow.IsNull("工程项目简称") Then

            e.DataRow("工程项目编号") = Nothing

        Else

            Dim d As Date = e.DataRow("开工日期")

            Dim y As Integer = d.Year

            Dim m As Integer = d.Month

            Dim Days As Integer = Date.DaysInMonth(y,m)

            Dim fd As Date = New Date(y,m,1) \'获得该月的第一天

            Dim ld As Date = New Date(y,m,Days) \'获得该月的最后一天

            Dim bh As String = e.DataRow("工程项目简称") & "-" & Format(d,"yyyyMM") & "-" \'生成编号的前缀

        If e.DataRow("工程项目编号").StartsWith(bh) = False \'如果工程项目编号前缀不符

                Dim max As String

                Dim idx As Integer

                Dim flt As String

                flt = "工程项目简称 = \'"& e.DataRow("工程项目简称") & "\' And 开工日期 >= #" & fd & "# And 开工日期 <= #" & ld & "# And [_Identify] <> " & e.DataRow("_Identify")

                max = e.DataTable.Compute("Max(工程项目编号)",flt) \'取得该月的相同工程代码的最大工程项目编号

                If max > "" Then \'如果存在最大工程项目编号

                   idx = CInt(max.Substring(19,4)) + 1 \'获得最大工程项目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("工程项目编号") = bh & Format(idx,"0000")

            End If

        End If

End Select

idx = CInt(max.Substring(19,4)) + 1 \'获得最大工程项目编号的后四位顺序号,并加1

改成

idx = CInt(max.Substring(bh.length,4)) + 1 \'获得最大工程项目编号的后四位顺序号,并加1