;with cte as
(
select ID,
substring(data, 1, 1) as Chars,
stuff(data, 1, 1, '') as data,
1 as RowID
from @t
union all
select ID,
substring(data, 1, 1) as Chars,
stuff(data, 1, 1, '') as data,
RowID + 1 as RowID
from cte
where len(data) > 0
)
select ID, RowID, Chars
from cte
order by ID, RowID