Teradata根据列使跟随动态

Question

我有一个表，其中包含列item，store，date和fcst。对于每个商品存储日，我需要对下一个x天的预测天数求和，但是每个商品存储组合的x发生变化。以下代码不起作用，建议我将X FOLLOWING替换为静态整数FOLLOWING：

不运行：

SELECT
ITEMNBR,
STORENBR,
DT,
SUM(FCST)OVER(PARTITION BY STORENBR,ITEMNBR ORDER BY DT BETWEEN CURRENT ROW AND X ROWS FOLLOWING) AS VALUE

FROM TABLENAME

运行：

SELECT
ITEMNBR,
STORENBR,
DT,
SUM(FCST)OVER(PARTITION BY STORENBR,ITEMNBR ORDER BY DT BETWEEN CURRENT ROW AND 7 ROWS FOLLOWING) AS VALUE

FROM TABLENAME

任何修复或建议的解决方法？