按下面思路实现。
但效率极差。
select * from
(
(select *, (select count(*) from a where 时间>=t.时间 ) as K from A t)
union all
(select *, (select count(*) from a where 时间>=t.时间 ) as K from B t)
union all
(select *, (select count(*) from a where 时间>=t.时间 ) as K from C t)
) v
order by k
limit 9
select * from A order by time desc limit 3
union all
select * from B order by time desc limit 3
union all
select * from C order by time desc limit 3
表里面连三条数据都没有 这得什么表啊