SELECT
 T1.PORT_CODE AS 港コード
,T3.PORT_NAME AS 港名
,T1.AMT AS 入国者数
,T2.AMT AS 出国者数
,T1.AMT - T2.AMT AS 差分
FROM (
	SELECT *
	FROM IMMIGRATION
	WHERE 
		GROUP_CODE = '120'
		AND KIND_CODE = '110' --入国者数
) T1
LEFT JOIN (
	SELECT *
	FROM IMMIGRATION
	WHERE 
		GROUP_CODE = '120'
		AND KIND_CODE = '120' --出国者数
) T2 
ON	T1.PORT_CODE = T2.PORT_CODE
AND T1.GROUP_CODE = T2.GROUP_CODE
LEFT JOIN PORT T3
ON T1.PORT_CODE = T3.PORT_CODE
WHERE T1.AMT - T2.AMT > 0
ORDER BY 5 DESC ,1 DESC