create procedure sys.sp_MSget_map_position
    @primary_key_bitmap varbinary(4000) = null,
    @index int,
    @colpos  sysname = NULL output,
    @art_col int = NULL output
as

    declare @this_col int
    declare @num_keys int
    declare @num_cols int

    select @this_col = 1
    select @num_keys = 0
    select @num_cols = datalength(@primary_key_bitmap) * 8

    select @colpos = null
    select @art_col = null

    while @this_col <= @num_cols
    begin
        if (substring(@primary_key_bitmap, 1 + (@this_col-1) / 8 , 1) &
            power(2, (@this_col-1) % 8 )) <> 0
        begin
            select @num_keys = @num_keys + 1
            if @num_keys = @index
            begin
                select @art_col = @this_col
                select @colpos = 'c' + convert(sysname, @this_col)
                break
            end
        end
        select @this_col = @this_col + 1
    end