Another problem with the subquery. What to do with aggregate functions?

Question

Oracle

Colleagues, tell me, is it possible to use aggregate functions in an attachment?
Query doesn't work(
Expected result: output order with earliest start time

select  order_id  from  t2
where t2.START_TIME=(
select min(t2.start_time) 
from t2)

Answer 1

Try this:
select order_gid from t2
where t2.START_TIME=(
select min(t3.start_time)
from t2 t3)

Answer 2

Aggregate functions must be used in conjunction with a group by clause. They can be used in a subquery.