SQL中random()将会生成0-1之间的随机小数，通过random()排序可得到随机排列的列表

select * from user order by random() desc;
select * from user order by user.id asc,random() desc;

若查询中添加了distinct去除重复，这要在select列上添加random()

select distinct *,random() from user order by random() desc;