SELECT
 a.PORT_CODE AS '港コード',
 PORT_NAME AS '港名',
 a.AMT AS '入国者数',
 b.AMT AS '出国者数',
 a.AMT - b.AMT AS '差分'
FROM
 IMMIGRATION AS a
INNER JOIN
 IMMIGRATION AS b
ON
 a.PORT_CODE = b.PORT_CODE
AND
 a.GROUP_CODE = b.GROUP_CODE
AND
 b.KIND_CODE = '120'
INNER JOIN
 PORT AS pt
ON
 a.PORT_CODE = pt.PORT_CODE
WHERE
 a.GROUP_CODE = '120'
AND
 a.KIND_CODE = '110'
AND
  a.AMT - b.AMT > 0
ORDER BY
  a.AMT - b.AMT  DESC,a.PORT_CODE DESC