SELECT 
    	 P.port_code AS 港コード
    	,P.port_name AS 港名
    	,SUM(
    		CASE I.kind_code
    			WHEN '110' THEN I.AMT
    		END
    	) AS 入国者数
    	,SUM(
    		CASE I.kind_code
    			WHEN '120' THEN I.AMT
    		END
    	) AS 出国者数
    	,SUM(   CASE I.kind_code WHEN '110' THEN I.AMT END) 
    	-
    	 SUM( CASE I.kind_code WHEN '120' THEN I.AMT END) 差分
    FROM
    	Port P
    INNER JOIN
    	IMMIGRATION I	
    ON
    	P.port_code = I.port_code
    INNER JOIN
    	GRP G
    ON
    	G.group_code = I.group_code
    GROUP BY
    	P.port_code	
    HAVING
        差分 > 0
    ORDER BY
        差分 DESC 
       ,港コード DESC