Update the ColumnNo field to display the same number when the AppID and FootNote are the same

I am trying to update the ColumnNo field to display the same number when the AppID and FootNote are the same. I need it to display like the first image below.

I have tried

ROW_NUMBER() Over (partition by AppID, FootNote Order by AppID) as RowNum

Which works in reverse.

And some other functions to no avail. How can I flip this?

Answer

Use dense_rank():

row_number() Over (order by AppID, FootNote) as RowNum