oracle union all

select rownum ,r.readdate,t.teacher_key ,t.teacher_name,t.department_key,t.department_name,t.position_,t.sort_num  
from oa_info_notice_readers r left join wp_kdb_teacher@kdb_link t 
  on r.readerid=t.teacher_key left join bpm_orgrolemembers@bpm_link a on t.teacher_name in(a.membername)
 where r.noticeid='7a3ba423-5920-4c92-9606-d34bba8de9d7'and a.rolenumber='RS004'
 union all
 select rownum, r.readdate,t.teacher_key ,t.teacher_name,t.department_key,t.department_name,t.position_,t.sort_num   
  from oa_info_notice_readers r left join wp_kdb_teacher@kdb_link t 
 on r.readerid=t.teacher_key where r.noticeid='7a3ba423-5920-4c92-9606-d34bba8de9d7' 
  and t.teacher_name not in(
  select t.teacher_name from oa_info_notice_readers r left join wp_kdb_teacher@kdb_link t 
  on r.readerid=t.teacher_key left join bpm_orgrolemembers@bpm_link a on t.teacher_name in(a.membername)
 where r.noticeid='7a3ba423-5920-4c92-9606-d34bba8de9d7'and a.rolenumber='RS004')