来自 table 的计数（列）在配置单元中的排名

Question

如果我想从 hive 中的 table select count(user_name), country。我应该使用什么命令来获得最多 user_name 的前 2 个国家/地区的结果？

如何使用排名功能？

id | user_name | country
 1 | a         | UK
 2 | b         | US
 3 | c         | AUS
 4 | d         | ITA
 5 | e         | UK
 6 | f         | US

结果应该是：

rank| num_user_name | country
 1  | 2             | US
 1  | 2             | UK
 2  | 1             | ITA
 2  | 1             | AUS

Answer 1

您可以使用 dense_rank 分析函数：

with cte as (
    select   country, 
             count(user_name) as num_user_name
    from     tbl
    group by country
), cte2 as (
    select   dense_rank() over (order by num_user_name desc) as ranked,
             num_user_name,
             country
    from     cte
)
select   ranked,
         num_user_name,
         country
from     cte2
where    ranked <= 2
order by 1

Answer 2

不需要子查询：

select dense_rank() over (order by count(*)) as rank,
       country, 
       count(*) as num_user_name
from t
group by country
order by count(*) desc, country;

来自 table 的计数（列）在配置单元中的排名

Rank in hive from count(column) from table

sql

hive

rank