select 
 p.PORT_CODE as 港コード
,p.PORT_NAME as 港名
,i.in_amt as 入国者数
,i.out_amt as 出国者数 
,i.in_amt-i.out_amt as 差分
from PORT p
inner join (select i.PORT_CODE
			,sum(case when i.KIND_CODE='110' then AMT else 0 end) in_amt
			,sum(case when i.KIND_CODE='120' then AMT else 0 end) out_amt
			from IMMIGRATION i
			where i.GROUP_CODE = '120'
			group by i.PORT_CODE) i
	on  p.PORT_CODE = i.PORT_CODE
order by 
 (i.in_amt-i.out_amt) desc
,p.PORT_CODE desc