SELECT IM.PORT_CODE AS 港コード
,PO.PORT_NAME AS 港名
,IMIN.AMT AS 入国者数
,IM.AMT AS 出国者数
,IMIN.AMT - IM.AMT AS 差分
FROM IMMIGRATION AS IM
LEFT JOIN PORT AS PO
ON IM.PORT_CODE = PO.PORT_CODE
LEFT JOIN GRP AS GRP
ON IM.GROUP_CODE = GRP.GROUP_CODE 
INNER JOIN IMMIGRATION AS IMIN
ON IMIN.PORT_CODE = IM.PORT_CODE 
AND IMIN.GROUP_CODE  = IM.GROUP_CODE 
AND IMIN.GROUP_CODE = '120'
AND IMIN.KIND_CODE = '110'
WHERE IM.GROUP_CODE = '120'
AND IM.KIND_CODE = '120'
AND 差分> 0

ORDER BY 差分 DESC
,港コード DESC