SELECT 
    I.PORT_CODE AS 港コード,
    P.PORT_NAME AS 港名,
    --外国人入国者のAMT AS 入国者数
    --外国人出国者のAMT AS 出国者数
    --外国人入国者のAMT - 外国人出国者のAMTの計算結果 AS 差分
FROM IMMIGRATION I INNER JOIN PORT P ON I.PORT_CODE = P.PORT_CODE
WHERE GROUP_CODE = 120
ORDER BY 差分 DESC, I.PORT_CODE DESC;