MySQL LIMIT是在ORDER BY之前还是之后应用的? [英] Is MySQL LIMIT applied before or after ORDER BY?

问题描述

MySQL处理查询时，哪个先出现?

Which one comes first when MySQL processes the query?

一个例子:

SELECT pageRegions
FROM pageRegions WHERE(pageID=?) AND(published=true) AND (publishedOn<=?)
ORDER BY publishedON DESC
LIMIT 1';

即使记录与修订日期时间不匹配，如果在ORDER BY之后应用了LIMIT，是否还会返回上次发布的pageRegion?

Will that return the last published pageRegion even if the record does not match the revision datetime IF LIMIT is applied after ORDER BY?

推荐答案

是的，它在ORDER BY之后.对于您的查询，您将获得记录的publishedOn最高的记录，因为您要订购DESC，从而使结果集中的最大值最大，然后从中选择第一个.

Yes, it's after the ORDER BY. For your query, you'd get the record with the highest publishedOn, since you're ordering DESC, making the largest value first in the result set, of which you pick out the first one.

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