create function interval(i int)
returns table (n int)
language sql
return
with t (n) as 
(
values ( 1 )
  union all
select n+ 1 
from t
where n<i
)
select n from t;

merge into <table> t using
(
select a.<pk>
, max
(
case t.n
  when  1  then d1
  ...
  when  8  then d8
end
) d9
from <table> a, table(interval( 8 )) t(n)
group by a.<pk>
) g on g.<pk>=t.<pk>
when matched then update set d9=g.d9
else ignore;