Mysql 随机查询10条数据效率最快的查询方法

1）使用join 和 rand() 耗时 0.009

SELECT

*

FROM

`t_topic` AS t1

JOIN (

SELECT

ROUND(

RAND() * (

(SELECT MAX(id) FROM `t_topic`) - (SELECT MIN(id) FROM `t_topic`)

) + (SELECT MIN(id) FROM `t_topic`)

) AS id

) AS t2

WHERE

t1.id >= t2.id

ORDER BY

t1.id

LIMIT 10;

2) 下面这条比上面那个还要慢几秒

SELECT * FROM `t_topic`

WHERE id >= (SELECT floor( RAND() * ((SELECT MAX(id) FROM `t_topic`)-(SELECT MIN(id) FROM `t_topic`)) + (SELECT MIN(id) FROM `t_topic`)))

ORDER BY id LIMIT 10;

3）或者使用下面这个也可以测试也是 耗时0.0012

SELECT

*

FROM

`t_topic`

WHERE

id >= (

SELECT

floor(

RAND() * (SELECT MAX(id) FROM `t_topic`)

)

)

ORDER BY

id

LIMIT 10;