select + order by + union + select + order by

select ...
order by ...
union
select ...
order by ...

(select * from dual
order by dummy)

with t1 as
(
select 2 f from dual union all
select 1 from dual union all
select 3 from dual 
),
t2 as
(
select 4 f from dual union all
select -1 from dual union all
select 5 from dual 
)
select 0 s, t1.f from t1
union 
select 1 s, t2.f from t2

         S          F
---------- ----------
         0          1
         0          2
         0          3
         1         -1
         1          4
         1          5
 
6 rows selected