with tbl as (
    select 
        i.port_code,
        p.port_name,
        max(case when kind_code = 110 then amt else 0 end) as amt_in,
        max(case when kind_code = 120 then amt else 0 end) as amt_out
    from immigration i
    join grp g on i.group_code = g.group_code
    join port p on i.port_code = p.port_code
    group by 1, 2
    having amt_in is not null and amt_out is not null
)

select
    port_code as '港コード',
    port_name as '港名',
    amt_in as '入国者数',
    amt_out as '出国者数',
    amt_in - amt_out as '差分'
from tbl
where amt_in >= amt_out
order by 5 desc, 1 desc;