create table rfd_test
(
     rid int primary key,
     rname varchar2(20) not null,
     rscore float not null
)
select * from rfd_test;
insert into rfd_test values(1,'rfd1',20);
insert into rfd_test values(2,'rfd1',88);
insert into rfd_test values(3,'rfd2',90);
insert into rfd_test values(4,'rfd2',90);
insert into rfd_test values(5,'rfd3',20);
insert into rfd_test values(6,'rfd4',990);
insert into rfd_test values(7,'rfd3',60);
commit;
--查出各科分数大于80的人(只用一条语句输出)
select distinct rname from rfd_test where rname not in
(select distinct rname from rfd_test where rscore <=80)