select
IM.PORT_CODE AS "港コード",
PO.PORT_NAME AS "港名",
SUM(CASE WHEN IM.KIND_CODE = "110" THEN IM.AMT ELSE 0 END) AS "入国者数",
SUM(CASE WHEN IM.KIND_CODE = "120" THEN IM.AMT ELSE 0 END) AS "出国者数",
SUM(CASE WHEN IM.KIND_CODE = "110" THEN IM.AMT ELSE 0 END) - SUM(CASE WHEN IM.KIND_CODE = "120" THEN IM.AMT ELSE 0 END) "差分"
from IMMIGRATION AS IM
inner join PORT PO on IM.PORT_CODE = PO.PORT_CODE
where IM.GROUP_CODE = "120"
group by 
IM.PORT_CODE,
PO.PORT_NAME
having 
SUM(CASE WHEN IM.KIND_CODE = "110" THEN IM.AMT ELSE 0 END) - SUM(CASE WHEN IM.KIND_CODE = "120" THEN IM.AMT ELSE 0 END) > 0
order by 
"差分" desc,
IM.PORT_CODE desc