SELECT
i.PORT_CODE AS 港コード,
p.PORT_NAME AS 港名,
SUM(CASE WHEN GROUP_CODE = '110' THEN AMT ELSE 0 END) AS 入国者数,	
SUM(CASE WHEN GROUP_CODE = '120' THEN AMT ELSE 0 END) AS 出国者数,
SUM(CASE WHEN GROUP_CODE = '110' THEN AMT ELSE 0 END) - SUM(CASE WHEN GROUP_CODE = '120' THEN AMT ELSE 0 END) AS 差分
FROM IMMIGRATION AS i
INNER JOIN PORT AS p
ON i.PORT_CODE = p.PORT_CODE
GROUP BY i.PORT_CODE
HAVING 差分 > 0
ORDER BY 差分, i.PORT_CODE