MySQL 如何处理查询中的 ORDER BY 和 LIMIT?

How does MySQL process ORDER BY and LIMIT in a query?(MySQL 如何处理查询中的 ORDER BY 和 LIMIT?)

问题描述

我有一个类似这样的查询:

I have a query that looks like this:

SELECT article FROM table1 ORDER BY publish_date LIMIT 20

ORDER BY 是如何工作的?是对所有记录进行排序，然后获取前 20 条记录，还是获取 20 条记录并按 publish_date 字段排序?

How does ORDER BY work? Will it order all records, then get the first 20, or will it get 20 records and order them by the publish_date field?

如果是最后一篇，则不能保证您真的能获得最近的 20 篇文章.

If it's the last one, you're not guaranteed to really get the most recent 20 articles.

推荐答案

它会先排序，然后获取前 20 个.数据库也会在 ORDER 之前处理 WHERE 子句中的任何内容BY.

It will order first, then get the first 20. A database will also process anything in the WHERE clause before ORDER BY.

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