WITH

NYUKOKU AS (
 SELECT PORT_CODE, AMT
 FROM IMMIGRATION
 WHERE KIND_CODE = '110'
 GROUP BY PORT_CODE
),

SYUKOKU AS (
 SELECT PORT_CODE, AMT
 FROM IMMIGRATION
 WHERE KIND_CODE = '120'
 GROUP BY PORT_CODE
)

SELECT DISTINCT
  IM.PORT_CODE                 AS '港コード'
 ,P.PORT_NAME                  AS '港名'
 ,NYUKOKU.AMT                  AS '入国者数'
 ,SYUKOKU.AMT                  AS '出国者数'
 ,(NYUKOKU.AMT - SYUKOKU.AMT ) AS '差分'
FROM
 IMMIGRATION AS IM
LEFT OUTER JOIN PORT AS P
ON P.PORT_CODE = IM.PORT_CODE
LEFT OUTER JOIN NYUKOKU
ON IM.PORT_CODE = NYUKOKU.PORT_CODE
LEFT OUTER JOIN SYUKOKU
ON IM.PORT_CODE = SYUKOKU.PORT_CODE
WHERE
 NYUKOKU.AMT >= SYUKOKU.AMT
ORDER BY
  (NYUKOKU.AMT - SYUKOKU.AMT ) DESC
 ,IM.PORT_CODE DESC