select c.cname
from   customers c
where  not exists (
         select pno
         from   parts p
         where  p.price < o.ono and
                not exists (
                   select c.cno
                   from   orders o, odetails od
                   where  o.ono = od.ono and
                          o.cno = c.cno and
                          od.pno = p.pno));


