Benutze so viele UNION ALL's wie nötig um die Daten zu konkatinieren:
select '---new colleagues---' ename, NULL job, NULL hiredate
from dual
UNION ALL
select ename, job, to_char (hiredate, 'DD.MM.YYYY')
from emp where hiredate >= to_date ('01.07.1981', 'DD.MM.YYYY')
UNION ALL
select '---before 07/81---' ename, NULL job, NULL hiredate
from dual
UNION ALL
select ename, job, to_char (hiredate, 'DD.MM.YYYY')
from emp where hiredate < to_date ('01.07.1981', 'DD.MM.YYYY')
Viel Spass damit
Gerd