主题：查找单据编号第一次和最后一次出位的行

如果在原来的代码修改，参考

Dim Names As New List(Of String)
For Each r As Row In Tables(e.Form.name & "_table2").Rows
    If Names.Contains(r("单据编号"))= False Then
        Names.Add(r("单据编号"))
    End If
Next

Dim i As Integer = 0
For Each nm As String In names
    For Each r As Row In Tables(e.Form.name & "_table2").Rows
        If nm = r("单据编号") Then
            msgbox("第一次" & r.Index)
            i=i+1

            Exit for
        End If
    Next
    MessageBox.Show("最后一次" & r.index)
Next