SELECT
PO.PORT_CODE AS 港コード
, PO.PORT_NAME AS 港名
, EN.AMT AS 入国者数
, EX.AMT AS 出国者数
, (EN.AMT - EX.AMT) AS 差分
FROM
	(select
	 PORT_CODE
	 ,GROUP_CODE
	 ,KIND_CODE
	 ,AMT
	 from
	 IMMIGRATION
	 where
	 KIND_CODE = 110
	 ) AS EN
INNER JOIN
	(select
	 PORT_CODE
	 ,GROUP_CODE
	 ,KIND_CODE
	 ,AMT
	 from
	 IMMIGRATION
	 where
	 KIND_CODE = 120
	 ) AS EX
ON EN.PORT_CODE = EX.PORT_CODE
INNER JOIN
PORT PO ON PO.PORT_CODE = EN.PORT_CODE
WHERE
EN.AMT >= EX.AMT
GROUP BY
PO.PORT_CODE
ORDER BY
差分 DESC
, PO.PORT_CODE DESC;