SELECT
      IMMIGRATION.PORT_CODE AS '港コード'
	, PORT_NAME AS '港名'
    ,SUM(CASE WHEN KIND_CODE = '110' THEN AMT ELSE 0 END) AS '入国者数'
    ,SUM(CASE WHEN KIND_CODE = '120' THEN AMT ELSE 0 END) AS '出国者数'
    ,SUM(CASE WHEN KIND_CODE = '110' THEN AMT ELSE 0 END) -
    SUM(CASE WHEN KIND_CODE = '120' THEN AMT ELSE 0 END) AS '差分'

FROM IMMIGRATION
    INNER JOIN PORT
        ON PORT.PORT_CODE = IMMIGRATION.PORT_CODE
group by
    IMMIGRATION.PORT_CODE

ORDER BY
      差分 desc
    , 港コード desc
;