MySQL 将 group 函数与 max() 一起使用无效

Question

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

SQL state [HY000]; error code [1111]; Invalid use of group function; nested exception is java.sql.SQLException: Invalid use of group function

这里是查询：

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()，我如何 return 布尔值？

Answer 1

您不能嵌套聚合函数，例如 SUM() 和 MAX()。您需要在子查询中执行内部查询。

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 将 group 函数与 max() 一起使用无效

MySQL Invalid use of group function with max()

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