Sql 如何在子查询中放置内部窗口函数

我试图对窗口函数的输出求和。问题是，当我尝试执行以下操作时，它会引发一个错误

SELECT 
    cm.cust_id,
    SUM(SUM(tr.FD_sales) OVER (partition by cm.cust_id order by tr.event_date range between interval 7 days preceding and current row)) AS T
FROM   
    campaign_engagement_history cm 
    LEFT JOIN 
    transactions_filtered tr ON cm.cust_id == tr.cust_id 
    AND DATE(tr.EVENT_DATE) BETWEEN DATE(date_add(cm.campaign_send_date, -90)) AND DATE(cm.campaign_send_date)   
GROUP BY
    cm.cust_id

有人对如何解决这个问题有什么建议吗？我不知道在子查询中使用窗口函数会是什么样子

这就是错误：

It is not allowed to use a window function inside an aggregate function. Please use the inner window function in a sub-query.

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首先使用窗口函数选择查询，然后使用外部函数将其包装，以便使用group by子句对窗口函数的值求和：

select cust_id,sum(T) from 
(
    SELECT 
        cm.cust_id,
        SUM(tr.FD_sales) OVER (partition by cm.cust_id order by tr.event_date range between interval 7 days preceding and current row) AS T
    FROM   
        campaign_engagement_history cm 
        LEFT JOIN 
        transactions_filtered tr ON cm.cust_id == tr.cust_id 
        AND DATE(tr.EVENT_DATE) BETWEEN DATE(date_add(cm.campaign_send_date, -90)) AND DATE(cm.campaign_send_date)   
) t
GROUP BY
    cust_id

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请提供样本数据和预期结果。不清楚你想做什么。@Sam Comber你试过这个吗？如果你面临更多的困难，请告诉我。