Is there any way to have a subquery return multiple columns in oracle db? (I know this specific sql will result in an error, but it sums up what I want pretty well)
you can use cross apply
:
select
a.x,
bb.y,
bb.z
from
a
cross apply
( select b.y, b.z
from b
where b.v = a.v
) bb
If there will be no row from b to mach row from a then cross apply
wont return row. If you need such a rows then use outer apply
If you need to find only one specific row for each of row from a, try:
cross apply
( select top 1 b.y, b.z
from b
where b.v = a.v
order by b.order
) bb