mysql 百万数据 随机数抽取

SELECT * FROM `table`
WHERE id >= (SELECT floor(RAND() * (SELECT MAX(id) FROM `table`)))　
ORDER BY id LIMIT 1;

　　这下，效率又提高了，查询时间只有0.01秒

　　最后，再把语句完善一下，加上MIN(id)的判断。我在最开始测试的时候，就是因为没有加上MIN(id)的判断，结果有一半的时间总是查询到表中的前面几行。

　　完整查询语句是：

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