SELECT
    T01.PORT_CODE AS 港コード
  , PORT.PORT_NAME AS 港名
  , T01.入国者数
  , T01.出国者数
  , T01.入国者数 - T01.出国者数 AS 差分
FROM
    (
    SELECT
        PORT_CODE
      , MAX(CASE when KIND_CODE = '110' THEN AMT ELSE 0 END) AS 入国者数
      , MAX(CASE When KIND_CODE = '120' THEN AMT ELSE 0 END) AS 出国者数
    FROM
        IMMIGRATION
    WHERE
        GROUP_CODE = '120'
    GROUP BY
        PORT_CODE
    ) T01
  , PORT
WHERE
    T01.PORT_CODE = PORT.PORT_CODE
AND 差分 > 0
ORDER BY
    差分 DESC
  , T01.PORT_CODE DESC