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mysql大数据高效随机代码_mysql高效率随机获取n条数据写法

时间：2023年10月14日

来源：网络

编辑：佚名

ID连续的情况下（注意不能带where，否则结果不好）：
select a.* from xx a join (select round((select max(id) from xx) * rand()) as rid from xx limit 110) b where a.id = b.rid;
SELECT *
FROM `mm_account` AS t1 JOIN (SELECT ROUND(RAND() * (SELECT MAX(id) FROM `mm_account`)) AS id) AS t2
WHERE
t1.id >=
t2.id
ORDER BY
t1.id ASC LIMIT 4;
ID不连续的情况下：
SELECT * FROM `mm_account`
WHERE id >= (SELECT floor(RAND() * (SELECT MAX(id) FROM `mm_account`))) and city="city_91" and showSex=1
ORDER BY id LIMIT 4;
假设你的表叫做mm_account，并且有一个字段叫id。最快的方法如下（随机获取5条）：
SELECT * FROM mm_account WHERE id >= ((SELECT MAX(id) FROM mm_account)-(SELECT MIN(id) FROM mm_account)) * RAND() + (SELECT MIN(id) FROM mm_account) limit 5;
如果带where语句，上面就不适合了。带where语句请看下面：
SELECT *
FROM `mm_account` AS t1 JOIN (SELECT ROUND(RAND() * (
(SELECT MAX(id) FROM `mm_account` where id<1000 )-(SELECT MIN(id) FROM `mm_account` where id<1000 ))+(SELECT MIN(id) FROM `mm_account` where id<1000 )) AS id) AS t2
WHERE
t1.id >=
t2.id
ORDER BY
t1.id LIMIT 5;

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