with IMMIGRATION_MD AS (
    SELECT
        im.PORT_CODE
        ,po.PORT_NAME
        ,SUM(CASE WHEN im.KIND_CODE = '110' THEN AMT ELSE 0 END) AS 入国者数
        ,SUM(CASE WHEN im.KIND_CODE = '120' THEN AMT ELSE 0 END) AS 出国者数
    FROM IMMIGRATION im
        INNER JOIN PORT po
    ON im.PORT_CODE = po.PORT_CODE
        WHERE im.GROUP_CODE = '120'
        GROUP BY im.PORT_CODE
)
SELECT
    PORT_CODE AS 港コード
    ,PORT_NAME AS 港名
    ,入国者数
    ,出国者数
    ,出国者数 - 入国者数 AS 差分
FROM IMMIGRATION_MD
WHERE 0 < 差分
ORDER BY 差分 DESC
    ,PORT_CODE DESC;