Hive 查询以获取最大计数

Posted 2023-04-18

【中文标题】Hive 查询以获取最大计数

【英文标题】：Hive query to get max of count

【发布时间】：2014-07-15 11:14:07

【问题描述】：

我的输入文件是这样的：

id,phnName,price,model
1,iphone,2000,abc
2,iphone,3000,abc1
3,nokia,4000,abc2
4,sony,5000,abc3
5,nokia,6000,abc4
6,iphone,7000,abc5
7,nokia,8500,abc6

我想编写一个配置单元查询来获取特定手机的最大计数。

输出：

iphone 3
nokia 3

到目前为止，我已经尝试了以下查询：

select d.phnName,count(*) from phnDetails d group by d.phnName

得到这样的输出：

iphone 3
nokia 3
sony 1

帮助我只检索最大值。

【问题讨论】：

提供了如下答案，请查看并告诉我

【参考方案1】：

我的查询正在运行

输入

1,iphone,2000,abc
2,iphone,3000,abc1
3,nokia,4000,abc2
4,sony,5000,abc3
5,nokia,6000,abc4
6,iphone,7000,abc5
7,nokia,8500,abc6

工作查询

select c.phnName, c.counter 
from 
(select d.phnName as phnName, count(*) as counter from phnDetails d group by d.phnName ) c 
join 
(select max(f.counter) as countmax from
(select cnt.phnName as phnName, count(*) as counter from phnDetails cnt group by cnt.phnName ) f) g 
where c.counter = g.countmax;

不确定它是否经过优化，但它按预期工作

输出如下，

使用以下步骤解决，如果回答了您的问题，请将其标记为已回答

CREATE TABLE phnDetails ( id INT, phnName STRING, price INT, details STRING)
ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' STORED AS TEXTFILE;

LOAD DATA LOCAL INPATH '/home/training/Phone/phones.txt' OVERWRITE INTO TABLE phnDetails;

select * from phnDetails;


select d.phnName, count(*) from phnDetails d group by d.phnName;


select c.phnName, c.counter from 
(select d.phnName as phnName, count(*) as counter from phnDetails d group by d.phnName ) c ;

select max(f.counter) as countmax from
(select cnt.phnName as phnName, count(*) as counter from phnDetails cnt group by cnt.phnName ) f ;

select max(f.counter) as countmax from
(select cnt.phnName as phnName, count(*) as counter from phnDetails cnt group by cnt.phnName ) f ;

select c.phnName, c.counter 
from 
(select d.phnName as phnName, count(*) as counter from phnDetails d group by d.phnName ) c 
join 
(select max(f.counter) as countmax from
(select cnt.phnName as phnName, count(*) as counter from phnDetails cnt group by cnt.phnName ) f) g 
where c.counter = g.countmax;

【讨论】：

感谢您将我的解决方案标记为已回答，您能否也为我的解决方案投票。感谢您的快速确认