Mysql 查询排名 (RowNumber) 和分组

Question

我有提到的类似问题in this thead

但它在 SQL Server 中，而 Mysql 不支持“分区依据”，因为我现在知道我能做什么？这是问题:

我有一个包含一些列的表:用户、类别、值

我想要进行一个查询，该查询将按值对所有用户进行排名，但会针对类别进行重置。

示例:

user1   CategoryA    10

user2   CategoryA    11

user3   CategoryA    9

user4   CategoryB    3

user1   CategoryB    11

查询将返回:

Rank   User     Category  
1     user2   CategoryA

2     user1   CategoryA

3     user3   CategoryA

1     user1   CategoryB

2     user4   CategoryB

有什么想法吗？

Answer 1

编辑2:基于OP的评论:

it worked with just a little bit wrong ranking and that's in the first rank.when similar categories with same value has the top rank one of them is the first in the rank and other is 2nd but they must have the first rank (1)

建议进行以下更改:

select rank, user, category, value
from (
  select user, @cc:=category category, @cv:=value value
    , case when @pc=@cc and @pv=@cv then @rn:=@rn
           when @pc=@cc and @pv!=@cv then @rn:=(@rn+1)
           else @rn:=1
      end as rank
    , @pc:=@cc as temp_currCat
    , @pv:=@cv as temp_currVal
  from user_category_values,
       (select @pc:='', @cc:='', 
               @pv:='', @cv:='', 
               @rn:=0) row_nums
  order by category asc, value desc
) results;

演示 @ MySQL 5.5.32 Fiddle