Select e.DataCol.Name
Case "下单日期","单据类型"
If e.DataRow.IsNull("下单日期") OrElse e.DataRow.IsNull("单据类型") Then
e.DataRow("订单号") = Nothing
Else
Dim d As Date = e.DataRow("下单日期")
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("单据类型") & "-" & Format(d,"yyyyMM") & "-" '生成编号的前缀
If e.DataRow("订单号").StartsWith(bh) = False '如果订单号前缀不符
Dim max As String
Dim idx As Integer
Dim flt As String
flt = "单据类型 = '"& e.DataRow("单据类型") & "' And 下单日期 >= #" & fd & "# And 下单日期 <= #" & ld & "# And [_Identify] <> " & e.DataRow("_Identify")
max = e.DataTable.Compute("Max(订单号)",flt) '取得该月的相同单据类型的最大订单号
If max > "" Then '如果存在最大订单号
idx = CInt(max.Substring(10,4)) + 1 '获得最大订单号的后四位顺序号,并加1
Else
idx = 1 '否则顺序号等于1
End If
e.DataRow("订单号") = bh & Format(idx,"0000")
End If
End If
End Select