用平均分数更新MYSQL

我有两个表fluids和cas，我正在尝试用cad表中的平均分数更新一个相关的表fluids。大概是这样的：

UPDATE fluids INNER JOIN cas on cas.cas = fluids.cas 
SET fluids.score = avg(cas.score) GROUP BY cas.cas

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您需要将聚合选择包装为子查询：

UPDATE fluids 
INNER JOIN (
    SELECT cas,avg(cas.score) as avg_score
    FROM cas
    GROUP BY cas 
) as c ON c.cas = fluids.cas 
SET fluids.score = c.avg_score

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是否确实要存储可轻松“动态”计算的数据？