WITH IMMIG AS (
    SELECT
        *
    FROM 
        IMMIGRATION
    WHERE 
        GROUP_CODE = 120
        AND KIND_CODE = 110
    )

, EMMIG AS (
    SELECT
        *
    FROM 
        IMMIGRATION
    WHERE 
        GROUP_CODE = 120
        AND KIND_CODE = 120
    )

SELECT
    p.PORT_CODE AS '港コード',
    PORT_NAME AS '港名',
    i.AMT AS '入国者数',
    e.AMT AS '出国者数',
    i.AMT - e.AMT AS '差分'
FROM
    IMMIG AS i
    INNER JOIN PORT AS p ON i.PORT_CODE = p.PORT_CODE
    INNER JOIN EMMIG AS e ON i.PORT_CODE = e.PORT_CODE 
WHERE
    i.AMT > e.AMT
ORDER BY
    i.AMT - e.AMT DESC 
;