-- 1. Group By, Keep --
SELECT a.item_cd
     , SUBSTR(MAX(b.recv_date), 1, 6) yyyymm
     , MAX(a.recv_price) KEEP(DENSE_RANK LAST ORDER BY b.recv_date) recv_price
  FROM tb_cmsm_a_032 a
  LEFT OUTER JOIN tb_cmsm_a_030 b
    ON a.saup_cd = b.saup_cd
   AND a.recv_no = b.recv_no
 WHERE a.item_cd = '921000163'
 GROUP BY a.item_cd
;
-- 2. Row_number --
SELECT item_cd
     , SUBSTR(recv_date, 1, 6) yyyymm
     , recv_price
  FROM (SELECT a.item_cd
             , b.recv_date
             , a.recv_price
             , ROW_NUMBER() OVER(ORDER BY b.recv_date DESC) rn
          FROM tb_cmsm_a_032 a
          LEFT OUTER JOIN tb_cmsm_a_030 b
            ON a.saup_cd = b.saup_cd
           AND a.recv_no = b.recv_no
         WHERE a.item_cd = '921000163'
        )
 WHERE rn = 1
;
-- 3. Order By, Rownum
SELECT item_cd
     , SUBSTR(recv_date, 1, 6) yyyymm
     , recv_price
  FROM (SELECT a.item_cd
             , b.recv_date
             , a.recv_price
          FROM tb_cmsm_a_032 a
          LEFT OUTER JOIN tb_cmsm_a_030 b
            ON a.saup_cd = b.saup_cd
           AND a.recv_no = b.recv_no
         WHERE a.item_cd = '921000163'
         ORDER BY b.recv_date DESC
        )
 WHERE ROWNUM = 1
;