在条件之间匹配表中的两个记录时如何获取最大记录？

问题描述

with tb as(
select 1 as PPT_FROM,40 PPT_TO from dual
union
select 15 as PPT_FROM,40 PPT_TO from dual)
select * from tb
where 40 between PPT_FROM and PPT_TO;

现在输入的日期范围均为40或15，因此我想获取最大记录，即15 PPT_from和40 PPT_to

解决方法

我认为您想要order by和fetch：

select *
from tb
where 40 between FROM and TO
order by from desc
fetch first 1 row only;

在旧版本的Oracle（12之前的版本）中，您需要一个子查询：

select tb.*
from (select tb.*
      from tb
      where 40 between FROM and TO
      order by from desc
     ) tb
where rownum = 1;

请注意，FROM和TO是列的非常不好的名称，因为它们是SQL关键字。

,

您可以使用简单的GROUP BY语句获得预期的结果

查询

library(evmix)
hillplot(claims$cost)
pickandsplot(claims$cost)

结果

WITH
    tb
    AS
        (SELECT 1 AS PPT_FROM,40 PPT_TO FROM DUAL
         UNION
         SELECT 15 AS PPT_FROM,40 PPT_TO FROM DUAL)
  SELECT MAX (ppt_from) AS ppt_from,ppt_to
    FROM tb
   WHERE 40 BETWEEN PPT_FROM AND PPT_TO
GROUP BY ppt_to;