select
    imm.port_code as 港コード,
    port.port_name as 港名,
    imm.amt as 入国者数,
    imm2.amt as 出国者数,
    imm.amt - imm2.amt as 差分
from
    immigration as imm
    inner join 
        port
        on imm.port_code = port.port_code
    inner join
        immigration as imm2
        on imm.port_code = imm2.port_code and imm.group_code = imm2.group_code and imm2.kind_code = "120"
where
    imm.group_code = "120" and imm.kind_code = "110" and 差分 > 0
order by
    差分 desc, imm.port_code desc