select i.port_code as "港コード",
       port_name as "港名",
       max(case when kind_code = 110 and group_code = 120 then AMT else 0 end) as "入国者数",
       max(case when kind_code = 120 and group_code = 120 then AMT else 0 end) as "出国者数",
       max(case when kind_code = 110 and group_code = 120 then AMT else 0 end) - 
       max(case when kind_code = 120 and group_code = 120 then AMT else 0 end) as "差分"
from IMMIGRATION as i
left join port as p on p.port_code = i.port_code
group by 1,2
having max(case when kind_code = 110 and group_code = 120 then AMT else 0 end) - 
       max(case when kind_code = 120 and group_code = 120 then AMT else 0 end) > 0
order by 5 desc,1 desc