SELECT 
 YEAR_MONTH
-- 月次売上
,MONTH_AMT
-- 売上累計
,SUM(MONTH_AMT) OVER (ORDER BY YEAR_MONTH) AS CUML_AMT
-- 移動年計
,SUM(MONTH_AMT) OVER (ORDER BY YEAR_MONTH ROWS BETWEEN 11 PRECEDING AND CURRENT ROW) AS YEAR_MOVE_AMT 
FROM (
SELECT
 substr(SALES_DATE, 1, 7) AS YEAR_MONTH
,SUM(SALES_AMT) AS MONTH_AMT
FROM SALES
WHERE UPDATED_NO IS NULL
GROUP BY
 YEAR_MONTH
)
ORDER BY
 YEAR_MONTH