SELECT
  IM1.PORT_CODE AS "港コード",
  PT.PORT_NAME AS "港名",
  IM1.AMT AS "入国者数",
  IM2.AMT AS "出国者数",
  (IM1.AMT-IM2.AMT) AS "差分"
FROM
  IMMIGRATION AS IM1
  INNER JOIN IMMIGRATION AS IM2
    ON IM1.PORT_CODE = IM2.PORT_CODE
    AND IM1.GROUP_CODE = IM2.GROUP_CODE
    AND IM2.KIND_CODE = "120"
  INNER JOIN PORT AS PT
    ON IM1.PORT_CODE = PT.PORT_CODE
WHERE
  IM1.GROUP_CODE = "120"
  AND IM1.KIND_CODE = "110"
  AND "差分" > 0
ORDER BY
  "差分" DESC,
  IM1.PORT_CODE DESC
;