SELECT
    I_IN.PORT_CODE AS 港コード,
    P.PORT_NAME AS 港名,
    I_IN.AMT AS 入国者数,
    I_OUT.AMT AS 出国者数,
    (I_IN.AMT - I_OUT.AMT) AS 差分
FROM IMMIGRATION AS I_IN
INNER JOIN GRP AS G1 ON G1.GROUP_CODE = I_IN.GROUP_CODE
INNER JOIN IMMIGRATION AS I_OUT ON I_IN.PORT_CODE = I_OUT.PORT_CODE
INNER JOIN GRP AS G2 ON G2.GROUP_CODE = I_OUT.GROUP_CODE
INNER JOIN PORT AS P ON P.PORT_CODE = I_IN.PORT_CODE
WHERE
    I_IN.KIND_CODE = 110
    AND I_OUT.KIND_CODE = 120
    AND G1.GROUP_NAME = '外国人'
    AND G2.GROUP_NAME = '外国人'
    AND I_IN.AMT > I_OUT.AMT
    
ORDER BY
    差分 DESC,
    P.PORT_CODE DESC