处理彩票的最佳方式？

Question

我有一张叫做tickets的表，里面存储了所有购买的门票。 看起来像：

id      int    AI,primary
userid  int

现在，用户显然可以购买任意数量的门票，以增加他们的获胜几率。 现在只运行这个语句有什么问题吗

SELECT
    u.id AS winner FROM tickets t
LEFT JOIN users u ON t.user = u.id
ORDER BY RAND() LIMIT 1

对于这样的系统，MySQL 函数是否“真正”足够随机？

似乎有时当我运行查询时，同一个人被选中了很多。

Answer 1

http://dev.mysql.com/doc/refman/5.7/en/mathematical-functions.html#function_rand RAND() is not meant to be a perfect random generator. It is a fast way to generate random numbers on demand that is portable between platforms for the same MySQL version. RAND() is not meant to be a perfect random generator. It is a fast way to generate random numbers on demand that is portable between platforms for the same MySQL version.

另请注意，当您的表变大时，此查询将变得非常昂贵，因为它必须在返回之前对表中的每一行进行排序。