SELECT 
imm.PORT_CODE AS 港コード,
pt.PORT_NAME AS 港名,
SUM(CASE WHEN imm.KIND_CODE = '110' THEN imm.AMT ELSE 0 END) AS 入国者数,
SUM(CASE WHEN imm.KIND_CODE = '120' THEN imm.AMT ELSE 0 END) AS 出国者数,
SUM(CASE WHEN imm.KIND_CODE = '110' THEN imm.AMT ELSE 0 END) - SUM(CASE WHEN imm.KIND_CODE = '120' THEN imm.AMT ELSE 0 END) AS 差分
FROM IMMIGRATION AS imm
INNER JOIN PORT AS pt
ON pt.PORT_CODE = imm.PORT_CODE
INNER JOIN GRP AS gp
ON gp.GROUP_CODE = imm.GROUP_CODE
WHERE gp.GROUP_CODE = '120'  -- 外国人
GROUP BY imm.PORT_CODE
HAVING SUM(CASE WHEN imm.KIND_CODE = '110' THEN imm.AMT ELSE 0 END) - SUM(CASE WHEN imm.KIND_CODE = '120' THEN imm.AMT ELSE 0 END)
ORDER BY SUM(CASE WHEN imm.KIND_CODE = '110' THEN imm.AMT ELSE 0 END) - SUM(CASE WHEN imm.KIND_CODE = '120' THEN imm.AMT ELSE 0 END) DESC,
    imm.PORT_CODE DESC