Question

我正在尝试选择一个布尔值，其中order.lastUpdated早于30分钟前，但我收到错误：

SQL状态[HY000];错误代码[1111];组功能使用无效; 嵌套异常是java.sql.SQLException：组的使用无效功能

以下是查询：

select 
c.externalReference channelReference,
c.id channelId,
max(o.lastUpdated) lastUpdated,
sum(if(max(o.lastUpdated) < date_sub(now(), interval 30 minute), 0, 1)) beforeThreshold
from channel c
join order_item o on c.id = o.channelId
where date(o.lastUpdated) = date(now())
and o.lastUpdated > date_sub(now(), interval 1 hour)
group by c.externalReference;

如果o.lastUpdated早于30分钟前我必须使用max()，我该如何返回布尔值？

Answer 1

您无法嵌套聚合函数，例如SUM()和MAX()。你需要在子查询中做内部的。

SELECT c.externalReference AS channelReference,
       c.id AS ChannelId
       o.lastUpdated,
       SUM(IF(o.lastUpdated < DATE_SUB(NOW(), INTERVAL 30 MINUTE), 0, 1) AS beforeThreshold
FROM channel AS c
JOIN (SELECT channelId, MAX(lastUpdated) AS lastUpdated
      FROM order_item
      WHERE DATE(lastUpdated) = TODAY()
        AND lastUpdated > DATE_SUB(NOW(), INTERVAL 1 HOUR)
      GROUP BY channelId) AS o
ON c.id = o.channelId
GROUP BY c.externalReference

MySQL使用max（）无效使用组函数

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