select I1.port_code as '港コード' 
                , P.port_name as '港名'
                , I1.amt as '入国者数'
                , I2.amt as '出国者数'
                , I1.amt - I2.amt as '差分'
         from immigration as I1 , immigration as I2 
         inner join port as P on P.port_code = I1.port_code
        where I1.port_code = I2.port_code
            and I1.kind_code = '110'    -- 入国者 
            and I2.kind_code = '120'    -- 出国者
            and I1.amt > I2.amt
            and I1.group_code = I2.group_code
            and I2.group_code = ( select G.group_code from GRP as G where G.group_name = '外国人' )    
        order by 5 desc , 1 desc