主题：为何这两组代码同时放在一起不执行

为何这两组代码同时放在一起不执行（DataColChanged）

Dim dr As DataRow =e.DataRow
Select e.DataCol.Name
    Case "日期","序号"
        If dr.IsNull("日期") OrElse dr.isnull("序号") Then
            dr("编号") = Nothing
        Else
            Dim drs As List(of DataRow) =e.DataTable.Select("日期 =#" & dr("日期") & "# and 序号 ='" & dr("序号") & "'" ,"_Identify")
            Dim i As Integer
            For Each tr As DataRow In drs
                Dim d As Date = tr("日期")
                Dim xh As Integer =tr("序号")
                Dim bh As String =  Format(d,"yyyyMMdd")  & format(xh,"000") '生成编号的前缀
                i =i+1
                tr("编号") = bh & format(i,"000")
            Next
        End If
End Select

If e.DataCol.Name = "机号"
    If e.DataRow.IsNull("机号") = False
        For Each dr As DataRow In e.DataTable.Select("[机号] Is null And [_Identify] < " & e.DataRow("_Identify"))
            dr("机号") = e.NewValue
        Next
    End If
End If

下载信息  [文件大小：   下载次数： ]

点击浏览该文件:管理项目1.table

没有机号列

楼主传错附件了：

推测了你的逻辑可能是这样的：

Dim dr As DataRow =e.DataRow
Select e.DataCol.Name
    Case "日期","序号"
        If dr.IsNull("日期") OrElse dr.isnull("序号") Then
            dr("编号") = Nothing
        Else
            Dim drs As List(of DataRow) =e.DataTable.Select("日期 =#" & dr("日期") & "# and 序号 ='" & dr("序号") & "'" ,"_Identify")
            Dim i As Integer
            For Each tr As DataRow In drs
                Dim d As Date = tr("日期")
                Dim xh As Integer =tr("序号")
                Dim bh As String =  Format(d,"yyyyMMdd")  & format(xh,"000") '生成编号的前缀
                i =i+1
                tr("编号") = bh & format(i,"000")
            Next
        End If
    Case "机号"
        If dr.IsNull("机号") = False Then
            Dim drs As List (of DataRow) = e.DataTable.Select("[机号] Is null And [ID] < " & e.DataRow("ID") & "")
            For Each dr1 As DataRow In drs
                dr1("机号") = e.NewValue
            Next
        End If
End Select

非常谢谢您给我的答案，根据您的答案我已解决：

下载信息  [文件大小：   下载次数： ]

点击浏览该文件:管理项目1(1).table

其中：编号为字符，序号为整数，[id]为[_Identify]