select
    imm.port_code as 港コード
    ,port.port_name as 港名
    ,sum(CASE WHEN imm.kind_code = "110" THEN imm.amt ELSE 0 END) as 入国者数
    ,sum(CASE WHEN imm.kind_code = "120" THEN imm.amt ELSE 0 END) as 出国者数
    ,sum(CASE WHEN imm.kind_code = "110" THEN imm.amt ELSE 0 END) - sum(CASE WHEN imm.kind_code = "120" THEN imm.amt ELSE 0 END) as 差分
from
    immigration as imm
inner join
    port on imm.port_code = port.port_code
inner join
    grp on imm.group_code = grp.group_code
WHERE
    grp.group_name = '外国人' and imm.kind_code in ("110","120")
group by
    imm.port_code
having
    差分 > 0
order by
    差分 desc, 港コード desc
;