MySQL 从 count() 中选择 max()
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select max() from count()
提问by Zdomb
Possible Duplicate:
every derived table must have its own alias
可能的重复：
每个派生表必须有自己的别名
I need to find maximum of actions per user
我需要找到每个用户的最大操作数
table columns: action_id, action_status, user
表列：action_id, action_status,user
request:
要求：
SELECT MAX(`counted`) FROM
(
SELECT COUNT(*) AS `counted`
FROM `table_actions`
WHERE `status` = "good"
GROUP BY `user`
)
error message: "Every derived table must have its own alias"
错误消息：“每个派生表都必须有自己的别名”
what is wrong?..
怎么了？..
回答by Michael Slade
That just means MySQL insists that you give the inner SELECTa name, like:
这只是意味着 MySQL 坚持你给内部SELECT一个名字，比如：
SELECT MAX(counted) FROM
(
SELECT COUNT(*) AS counted
FROM table_actions
WHERE status = "good"
GROUP BY user
) AS counts;
