CREATE TABLE C AS
SELECT NVL(A.id,b.id)
,LAST_VALUE(cola IGNORE NULLS) OVER(ORDER BY NVL(A.id,b.id)) AS cola
,LAST_VALUE(colb IGNORE NULLS) OVER(ORDER BY NVL(A.id,b.id)) AS colb
,colx
,coly
FROM A FULL JOIN B ON a.id=b.id;

select B.ID,A.ColA,A.ColB,B.ColX, B.colY FROM B
INNER JOIN
(SELECT B.ID,(SELECT Max(ID) FROM A WHERE ID<=B.ID) AS AID FROM B) C
ON B.ID=C.ID
LEFT Outer join A
ON A.ID=C.AID
UNION
select *, '','' FROM A
Order by ID

Select Case when B.ID IS NULL then A.ID else B.ID END ID, A.ColA, A.ColB, B.colX, B.colY
from
(Select ID, (Select ID From (Select ROW_NUMBER() over(order by ID) row,* from TA) A where A.row = temA.row +1) nextID, ColA, ColB from
(Select ROW_NUMBER() over(order by ID) row,* from TA) temA ) A
LEFT join TB B ON A.ID = B.ID
union
Select Case when B.ID IS NULL then A.ID else B.ID END ID, A.ColA, A.ColB, B.colX, B.colY
from
(Select ID, (Select ID From (Select ROW_NUMBER() over(order by ID) row,* from TA) A where A.row = temA.row +1) nextID, ColA, ColB from
(Select ROW_NUMBER() over(order by ID) row,* from TA) temA ) A
join TB B
ON (B.ID >A.ID AND B.ID < A.nextID ) OR (A.nextID IS NULL AND B.ID >= A.ID )

drop table #A
drop table #B

select 1 ID, 'AAA' colA, 'BBBBB' colB into #A
union
select 3, 'CCC', 'DDDDD'
union
select 5, 'DDD', 'FFF'
union
select 8, 'EEE', 'FFFFF'

select 2 ID, 'aaa' colX, 'bbbbb' colY into #B
union
select 4, 'ccc', 'ddddd'
union
select 5, 'sssss', 'd'
union
select 6, 'ffff', 'ddd'
union
select 7, 'adf', 'fghs'
union
select 9, 'ewt', 'qt'

select * from #A
select * from #B

select B.ID, colA, colB, colX, colY
from #A A,
(
select *, (select top 1 ID from #A where ID <= #B.ID order by ID desc) aID
from #B
) B
where A.ID = B.aID
union
select ID, colA, colB, null, null
from #A
where ID not in (select ID from #B)