WITH in_t AS(
    SELECT
        PORT_CODE
        , KIND_CODE
        , GROUP_CODE
        , AMT AS in_amt
    FROM
        IMMIGRATION
        INNER JOIN GRP USING(GROUP_CODE)
    WHERE
        KIND_CODE = '110'
        AND GROUP_CODE = '120'
), out_t AS(
    SELECT
        PORT_CODE
        , KIND_CODE
        , GROUP_CODE
        , AMT AS out_amt
    FROM
        IMMIGRATION
        INNER JOIN GRP USING(GROUP_CODE)
    WHERE
        KIND_CODE = '120'
        AND GROUP_CODE = '120'
)
SELECT
    PORT_CODE AS 港コード
    , PORT_NAME AS 港名
    , in_amt AS 入国者数
    , out_amt AS 出国者数
    , (in_amt - out_amt) AS 差分
FROM
    in_t
    INNER JOIN out_t USING(PORT_CODE)
    INNER JOIN PORT USING(PORT_CODE)
WHERE
    (in_amt - out_amt) > 0
ORDER BY 5 DESC, 1 DESC;