SELECT

    IMMIGRATION.PORT_CODE AS 港コード,
    PORT.PORT_NAME AS 港名,
    SUM(CASE WHEN IMMIGRATION.KIND_CODE = '110' THEN IMMIGRATION.AMT ELSE 0 END) AS 入国者数,
    SUM(CASE WHEN IMMIGRATION.KIND_CODE = '120' THEN IMMIGRATION.AMT ELSE 0 END) AS 出国者数,
    SUM(CASE WHEN IMMIGRATION.KIND_CODE = '110' THEN IMMIGRATION.AMT ELSE 0 END) - SUM(CASE WHEN IMMIGRATION.KIND_CODE = '120' THEN IMMIGRATION.AMT ELSE 0 END) AS 差分

    FROM IMMIGRATION INNER JOIN PORT ON IMMIGRATION.PORT_CODE = PORT.PORT_CODE
    
    GROUP BY IMMIGRATION.PORT_CODE
    --HAVING (SUM(CASE WHEN IMMIGRATION.GROUP_CODE = '110' THEN IMMIGRATION.AMT ELSE 0 END) - SUM(CASE WHEN IMMIGRATION.GROUP_CODE = '120' THEN IMMIGRATION.AMT ELSE 0 END)) > 0
    HAVING (入国者数 - 出国者数) > 0
    ORDER BY 差分 DESC, IMMIGRATION.PORT_CODE DESC;