sql - Oracle Sql获取另一列的每个不同值出现次数最多的值

Question

假设我有这张 table

language | offer
chinese  |   1
chinese  |   1
english  |   1
spanish  |   2
spanish  |   2
italian  |   2
french   |   3

我想要每个不同报价出现次数最多的语言，就像这样

language | offer
chinese  |   1
spanish  |   2
french   |   3

我如何在 oracle sql 中执行此操作？

Answer 1

这是一种使用公共(public)表表达式的方法。

SQL Fiddle

在第一个 cte 中，您计算​​按报价和语言分组的计数。 在下一个 cte 中，使用 rank 或 row_number 将 1 分配给具有最高语言计数的报价。 最后，从排名第一的行中选择。

with counts as(
select offer, language, count(*) cnt
from tablename
group by offer, language)
,ranking as
(select rank() over(partition by offer order by cnt desc) rnk
, c.*
from counts c)
select language, offer
from ranking 
where rnk = 1

没有窗口函数的替代方法:

with counts as (
select offer, language, count(*) cnt
from tablename
group by offer, language)
,maxcount as (select offer, max(cnt) mxcnt from counts group by offer)
select c.language, m.offer
from counts c
join maxcount m on m.offer = c.offer and m.mxcnt = c.cnt