Creo que me las arreglé para hacer esto con funciones analíticas (no elegantemente, pero no obstante) -
with
grps as(
select marker
from(
select collateral_num,
loan_num,
rownum as marker,
case when lead(loan_num,1) over (order by collateral_num) <> loan_num
and lead(collateral_num,1) over (order by collateral_num) <> collateral_num
then 1
when lead(loan_num,1) over (order by collateral_num) is null
then 1
else null end as grp
from loan
order by collateral_num
)
where grp is not null
)
, marked as(
select loan.*, grps.*, row_number() over(partition by marker order by collateral_num) as splitter
from loan, grps
)
select collateral_num,
min(collateral_num) over (partition by marker) as min_collateral_num,
loan_num
from marked y
where splitter <= marker
and (splitter > (select max(x.marker) from marked x where x.marker < y.marker)
or marker = (select min(marker) from marked))
Consulte sqlfiddle en http://sqlfiddle.com/#!4/cfb1a7/40/ 0
