SQL Max和Sum

Question

以下是我正在使用的查询：

SELECT 
   County,
   Code,
   Sum(PaidAmount) AS TotalPaid
FROM
   Counties
GROUP BY
   County,
   Code

返回集合：

County     Code         TotalPaid
Brown      99           210.21
Lyon       73           322.22
Lyon       88           533.22
Lincoln    22           223.21

我正在寻找的是一个查询，它将返回显示县的行和每个县的最大TotalPaid的代码。我需要的结果集的一个例子如下所示（注意里昂，自里昂以来被删除了73，88的总支付金额更高）：

County     Code         TotalPaid
Brown      99           210.21
Lyon       88           533.22
Lincoln    22           223.21

Answer 1

我无法测试这个，但RANK应该解决这个问题：

SELECT x.County, x.Code x.TotalPaid
    ,RANK() OVER 
    (PARTITION BY x.County ORDER BY x.TotalPaid DESC) AS 'RANK'
FROM

(SELECT 
   County,
   Code,
   Sum(PaidAmount) AS TotalPaid
FROM
   Counties
GROUP BY
   County,
   Code) x
WHERE Rank = 1

Answer 2

我认为你需要做类似下面的事情。在我复习我写的内容之前，我刚刚被叫走了，但希望它会给你足够的指针。一些RDBMS不允许“where country，TotalPaid = select value，value”构造但你可以解决这个问题

select 
   County,
   Code,
   TotalPaid
from (SELECT 
       County,
       Code,
       Sum(PaidAmount) AS TotalPaid
     FROM
       Counties
     GROUP BY
       County,
       Code ) tbl
 where County, TotalPaid = (select County, 
                                 max(TotalPaid)
                             FROM
                                 Counties
                             GROUP BY
                                 County,
                                 Code ) tbl2

Answer 3

   SELECT 
   c.County,
   c.Code,
   Sum(c.PaidAmount) AS TotalPaid
   FROM
   Counties c
   WHERE
   c.Code in (select max(c2.code) from counties c2 where c2.county = c.county)
   GROUP BY
   c.County,
   c.Code

这个应该可以工作，虽然我还没有测试过

Answer 4

您必须使用窗口函数来执行此操作。虽然你想要的东西很容易用英语表达，但遗憾的是它并不容易在SQL中表达。这应该做你需要的：

select
    County, Code, TotalPaid
from
(
SELECT 
   County,
   Code,
   sum(PaidAmount) AS TotalPaid
FROM
   Counties
GROUP BY
   County, Code
) source

where (row_number() over (partition by County order by TotalPaid desc)) = 1

Answer 5

这是一个更新的解决方案：

select c1.county, c1.code, c1.paidAmount 
from counties c1
inner join (
  select county, max(paidAmount) paidAmount 
  from counties 
  group by county) c2 
on c1.county=c2.county and c1.paidAmount=c2.paidAmount;

请注意，如果某个县有多个最高付款，则会返回共享该最大值的所有行。