create table t1 (CODE varchar2(20), NAME varchar2(10), t_date number(6));

insert into t1 values ('0001','AAA1',201001);
insert into t1 values ('0001','AAA2',201007);
insert into t1 values ('0002','BBB1',200902);
insert into t1 values ('0002','BBB2',201008);
commit;

select code,name,t_date
from
(select code,name,t_date,row_number() over(partition by code order by t_date) rn
from t1
where t_date >= 200907)
where rn=1

    code     name     t_date
----------------------------------
1    0001    AAA1    201001
2    0002    BBB2    201008