SELECT
    p.PORT_CODE AS 港コード,
    PORT_NAME AS 港名,
    SUM(CASE WHEN KIND_CODE = "110" THEN AMT ELSE 0 END) AS 入国者数,
    SUM(CASE WHEN KIND_CODE = "120" THEN AMT ELSE 0 END) AS 出国者数,
    SUM(CASE WHEN KIND_CODE = "110" THEN AMT ELSE 0 END) - SUM(CASE WHEN KIND_CODE = "120" THEN AMT ELSE 0 END) AS 差分
FROM IMMIGRATION AS i
JOIN GRP AS g
ON i.GROUP_CODE = g.GROUP_CODE
JOIN PORT AS p
ON i.PORT_CODE = p.PORT_CODE
WHERE GROUP_NAME = "外国人"
GROUP BY 港コード, 港名
HAVING 差分 > 0
ORDER BY 差分 DESC, 港コード DESC