SELECT
  II.PORT_CODE AS "港コード",
  P.PORT_NAME AS "港名",
  SUM(II.AMT) AS "入国者数",
  SUM(IO.AMT) AS "出国者数",
  ("入国者数" - "出国者数") AS "差分"
FROM
  IMMIGRATION AS II
INNER JOIN
  PORT AS P
  ON
    II.PORT_CODE = P.PORT_CODE
INNER JOIN
  IMMIGRATION AS IO
  ON
    II.PORT_CODE = IO.PORT_CODE AND
    IO.KIND_CODE = "120" AND
    IO.GROUP_CODE = "120"
WHERE
  II.KIND_CODE = "110" AND
  II.GROUP_CODE = "120" AND
  "差分" > 0
GROUP BY
  II.PORT_CODE
ORDER BY
  "差分" DESC,
  II.PORT_CODE DESC
;