select tt.* from
(select t.deptno from dept t
minus
select t.deptno from emp t) tt
union all
select tt.* from
(select t.deptno from emp t
minus
select t.deptno from dept t) tt
select tt.* from
(select t.deptno from dept t
minus
select t.deptno from emp t) tt
union all
select tt.* from
(select t.deptno from emp t
minus
select t.deptno from dept t) tt