mysql 从大量数据表中高效随机取n条数据

先上个SQL语句，后面补上实操和截图

SELECT *
FROM `tb1` AS t1 JOIN (SELECT ROUND(RAND() * (
(SELECT MAX(id) FROM `tb1)-(SELECT MIN(id) FROM tb1))+(SELECT MIN(id) FROM `tb1`)) AS id) AS t2
WHERE t1.id >= t2.id
ORDER BY t1.id LIMIT 1;