按部门划分后分组得分的最大值

Question

我的查询得到每个等级每个部门的员工数。

select dept , grade , count(1) CNT 
from mytable 
group by dept , grade 
order by dept , cnt desc; 

现在我需要从每个部门的最大数量得分。

输出应该

dept grades MAX(count) 

我该怎么办呢？

感谢

Answer 1

要做到这一点，最好的办法是使用row_number()功能：

select dept, grade, cnt 
from (select dept, grade, count(*) as cnt, 
      row_number() over (partition by dept order by count(*) desc) as seqnum 
     from mytable t 
     group by dept, grade 
    ) t 
where seqnum = 1