本文介绍了MySQL从60万行中快速选择10条随机行的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
如何最好地编写一个查询,该查询从总共60万行中随机选择10行?
How can I best write a query that selects 10 rows randomly from a total of 600k?
推荐答案
一篇出色的文章,介绍了从简单到有缺口,再到有缺口的不均匀情况的几种情况.
A great post handling several cases, from simple, to gaps, to non-uniform with gaps.
http://jan.kneschke.de/projects/mysql/order -by-rand/
在大多数情况下,这是您的操作方式:
For most general case, here is how you do it:
SELECT name
FROM random AS r1 JOIN
(SELECT CEIL(RAND() *
(SELECT MAX(id)
FROM random)) AS id)
AS r2
WHERE r1.id >= r2.id
ORDER BY r1.id ASC
LIMIT 1
这假设id的分布是相等的,并且id列表中可以有空白.有关更多高级示例,请参见文章
This supposes that the distribution of ids is equal, and that there can be gaps in the id list. See the article for more advanced examples
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