결과는 맞는데 제대로 이해한건지 모르겠네요. 생산일자를 넘지 않는 최근 생산일자라고 하셨는데 헷갈리는군요.

with t1 as (
select 'A' code, '20201020' dt, '1300' ti, '홍길동' nm from dual
union all select 'B', '20201021', '0910', '마징가' from dual
union all select 'C', '20201021', '1435', '홍길동' from dual
),
t2 as (
select 'A' code, to_date('2020-09-30 12:10:18','YYYY-MM-DD HH24:MI:SS') dt, 'AAA' nm from dual
union all select'A', to_date('2020-10-20 10:10:18','YYYY-MM-DD HH24:MI:SS'), 'BBB' from dual
union all select'A', to_date('2020-10-22 13:10:18','YYYY-MM-DD HH24:MI:SS'), 'AAA' from dual
union all select'B', to_date('2020-09-28 12:10:18','YYYY-MM-DD HH24:MI:SS'), 'CCC' from dual
union all select'B', to_date('2020-10-15 15:10:18','YYYY-MM-DD HH24:MI:SS'), 'AAA' from dual
union all select'B', to_date('2020-10-20 08:10:18','YYYY-MM-DD HH24:MI:SS'), 'DDD' from dual
union all select'B', to_date('2020-10-30 16:10:18','YYYY-MM-DD HH24:MI:SS'), 'CCC' from dual
union all select'C', to_date('2020-09-20 12:10:18','YYYY-MM-DD HH24:MI:SS'), 'EEE' from dual
union all select'C', to_date('2020-10-21 13:10:18','YYYY-MM-DD HH24:MI:SS'), 'ZZZ' from dual
union all select'C', to_date('2020-10-25 18:20:18','YYYY-MM-DD HH24:MI:SS'), 'AAA' from dual
)
select *
from (
      select t1.code, 
             t1.nm t1_nm, 
             t2.nm t2_nm, 
             t1.dt,
             row_number() over (partition by t1.code order by abs(t2.dt - to_date (t1.dt||t1.ti, 'YYYYMMDDHH24MI'))*24*60) rn
       from t1, t2 
      where t1.code = t2.code
     )
where rn=1

많은 도움됐습니다~

늦은밤 진심으로 감사드립니다~~^^!!

앞으로 공부 열심히 하도록 하겠습니다~ㅎ;;

SELECT a.code, a.nm, a.dt
     , MIN(b.nm) KEEP(DENSE_RANK LAST ORDER BY b.dt) b_nm
  FROM t1 a
     , t2 b
 WHERE b.code = a.code
   AND b.dt <= TO_DATE(a.dt || a.ti, 'yyyymmddhh24mi')
 GROUP BY a.code, a.nm, a.dt
;

마농님도 항상 감사합니다

건강하세요~~^^;;