每个月最受欢迎的品牌

• 首先计算每个月份的各个品牌的订单量
• 按月进行分组对订单量排序得出序号，并筛选

select 
*
from 
    (select 
    a.品牌
    ,a.mon
    ,a.num
    ,row_number()over(PARTITION by a.mon order by a.num desc) as num_rank   
    from  
        (SELECT 
        *
        ,date_format(日期,"%Y-%m-01") mon
        ,count(orser_id) num
        FROM `alcohol`
        group by 
        date_format(日期,"%Y-%m-01") ,品牌) a
    ) b
where b.num_rank<4 
order by b.mon asc