declare
  for_jobs varchar2(100);
begin
for_jobs := rtrim(:first_job);
for_jobs := for_jobs||rtrim(:sec_job);
for_jobs := for_jobs||rtrim(:third_job);
for_jobs := for_jobs||rtrim(:forth_job);
-- 
:disp_for_jobs := for_jobs;
-- 
for rec in (select empno, ename, job, deptno
              from emp
             where job in (for_jobs)
             order by 3,1 
            )
loop
	 message (rec.empno||', '||rec.ename||', '||rec.job||', '||rec.deptno);
	 pause;
end loop;
end;

for rec in (select empno, ename, job, deptno
              from emp
       where job in (rtrim(:first_job),rtrim(:sec_job).....)
             order by 3,1 
            )