编写SQL＆Hive查询以打印每个国家第二高薪的年份？

Question

写SQL和HIVE查询以打印每个国家第二高薪的年份？。

请提供下表查询

country,salary,year
india,1000,2017
japan,2000,2017
germany,1500,2017
india,1250,2018
japan,500,2018
china,955,2017
japan,850,2019
china,1150,2018
india,1250,2019

Answer 1

类似：

select 
    t.*
from (
    select
        tbl.*,
        row_number() over(partition by country order by salary desc) rn
    from 
        tbl
) t
where 
    t.rn = 2

Answer 2

最大的问题是您如何处理纽带。大概是第二高的工资。在这种情况下，您特别需要寻找dense_rank()窗口功能：

select t.*
from (select t.*,
             dense_rank() over (partition by country order by salary desc) as seqnum
      from t
     ) t
where t.seqnum = 2;

现在，这样做的挑战在于，如果发生平局，它可能返回不止一行。如果您特别想要一行，则：

select t.*
from (select t.*,
             dense_rank() over (partition by country order by salary desc) as ranking,
             row_number() over (partition by country, salary order by country) as seqnum
      from t
     ) t
where t.ranking = 2 and seqnum = 1;