用Sql语句实现查找一列中第N大值 select * from
(select t.*,dense_rank() over (order by sal) rank from employee)
where rank = N;
(select t.*,dense_rank() over (order by sal) rank from employee)
where rank = N;
意思是,得到每行以mid,id 为分组中的位置!
order by actid nulls last 只是个排序函数!