从mysql中随机读取多条记录

今日工作中需要一些随机数，当APP请求接口时，从数据库中随机读取多条数据给APP，经网上查询实践，大致以下三种查询：

1.随机读取连续多条记录。经过实践，可以随机读取多条连续的数据记录，里头取值的一般都是主键ID来进行最大值、最小值的读取：

SELECT * FROM b_user_send_rose_log  AS t1  JOIN (SELECT ROUND(RAND() * ((SELECT MAX(id) FROM b_user_send_rose_log)-(SELECT MIN(id) FROM b_user_send_rose_log))+(SELECT MIN(id) FROM b_user_send_rose_log)) AS id) AS t2 WHERE t1.id >= t2.id ORDER BY t1.id LIMIT 5;

2.随机多条数据。以下两种都是随机读取数据，查询数据速度、随机范围都基本相差不大

SELECT * FROM b_user_send_rose_log WHERE id >= ((SELECT MAX(id) FROM b_user_send_rose_log)-(SELECT MIN(id) FROM b_user_send_rose_log)) * RAND() + (SELECT MIN(id) FROM b_user_send_rose_log) LIMIT 5;

SELECT * FROM b_user_send_rose_log WHERE id>=(SELECT floor(RAND() * ((SELECT MAX(id) FROM b_user_send_rose_log)-(SELECT MIN(id) FROM b_user_send_rose_log)) + (SELECT MIN(id) FROM b_user_send_rose_log))) ORDER BY id LIMIT 5;