select
    TBL1.PORT_CODE as '港コード',
    TBL2.PORT_NAME as '港名',
    case when TBL1.GROUP_CODE='110' then TBL1.AMT else 0 end as '入国者数',
    case when TBL1.GROUP_CODE='120' then TBL1.AMT else 0 end as '出国者数',
    sum(case when TBL1.GROUP_CODE='110' then TBL1.AMT when TBL1.GROUP_CODE='120' then TBL1.AMT*-1 else 0 end) as '差分'
from
    IMMIGRATION as TBL1
inner join PORT as TBL2 on TBL1.PORT_CODE = TBL2.PORT_CODE
inner join GRP as TBL3 on TBL1.GROUP_CODE = TBL3.GROUP_CODE
group by
    TBL1.PORT_CODE,TBL2.PORT_NAME
order by '差分',TBL1.GROUP_CODE