SELECT
    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
JOIN PORT
USING (PORT_CODE)
JOIN GRP
USING (GROUP_CODE)
GROUP BY PORT_CODE
HAVING 差分 > 0
ORDER BY 差分 DESC, 港コード DESC
;