-- SQLite
SELECT
    PRT.PORT_CODE AS 港コード
    , PRT.PORT_NAME AS 港名
    , SUM(CASE WHEN IMM.KIND_CODE = "110" THEN IMM.AMT ELSE 0 END) AS 入国者数
    , SUM(CASE WHEN IMM.KIND_CODE = "120" THEN IMM.AMT ELSE 0 END) AS 出国者数
    , SUM(CASE WHEN IMM.GROUP_CODE = "120" THEN IMM.AMT ELSE 0 END) - SUM(CASE WHEN IMM.GROUP_CODE = "110" THEN IMM.AMT ELSE 0 END) AS 差分
FROM
    IMMIGRATION AS IMM
    INNER JOIN GRP AS GRP
        ON IMM.GROUP_CODE = GRP.GROUP_CODE
        AND GRP.GROUP_CODE = "120"
    INNER JOIN PORT AS PRT
        ON IMM.PORT_CODE = PRT.PORT_CODE
GROUP BY 
    PRT.PORT_CODE
HAVING
    差分 > 0
ORDER BY
    差分 DESC
    , PRT.PORT_CODE DESC
;