select * from tb_phone_no_prefix a
  where (a.prefix, a.isp, a.area) in
   (select prefix,isp, area from tb_phone_no_prefix group by prefix,isp, area having count(*) > 1)


  delete from tb_phone_no_prefix a
  where (a.prefix, a.isp, a.area) in
   (select prefix,isp, area from tb_phone_no_prefix group by prefix,isp, area having count(*) > 1)
  and id not in (select min(id) from tb_phone_no_prefix group by prefix,isp, area having count(*)>1)