如何结合GROUP BY和ROW_NUMBER？

Question

我希望下面的示例代码是不言自明的：

declare @t1 table (ID int,Price money, Name varchar(10))
declare @t2 table (ID int,Orders int,  Name varchar(10))
declare @relation  table (t1ID int,t2ID int)
insert into @t1 values(1, 200, 'AAA');
insert into @t1 values(2, 150, 'BBB');
insert into @t1 values(3, 100, 'CCC');
insert into @t2 values(1,25,'aaa');
insert into @t2 values(2,35,'bbb');
insert into @relation values(1,1);
insert into @relation values(2,1);
insert into @relation values(3,2);

select T2.ID AS T2ID
,T2.Name as T2Name
,T2.Orders
,T1.ID AS T1ID
,T1.Name As T1Name
,T1Sum.Price
FROM @t2 T2
INNER JOIN (
    SELECT Rel.t2ID
        ,MAX(Rel.t1ID)AS t1ID 
-- the MAX returns an arbitrary ID, what i need is: 
--      ,ROW_NUMBER()OVER(Partition By Rel.t2ID Order By Price DESC)As PriceList
        ,SUM(Price)AS Price
        FROM @t1 T1 
        INNER JOIN @relation Rel ON Rel.t1ID=T1.ID
        GROUP BY Rel.t2ID
)AS T1Sum ON  T1Sum.t2ID = T2.ID
INNER JOIN @t1 T1 ON T1Sum.t1ID=T1.ID

结果：

T2ID   T2Name   Orders  T1ID    T1Name  Price     
 1      aaa       25     2       BBB    350,00     
 2      bbb       35     3       CCC    100,00

我需要的是上面的评论，一种获得

ROW_NUMBER

但首先也是

Group By

的方法。所以我需要在关系表中按

sum

分组的所有T1价格的

T2.ID

和在外部查询中价格最高的

t1ID

。

换句话说：如何将

MAX(Rel.t1ID)AS t1ID

改成有点返回价格最高的ID？

所以期望的结果是（注意第一个 T1ID 从 2 变为 1，因为它具有更高的价格）：

T2ID   T2Name   Orders  T1ID    T1Name  Price     
 1      aaa       25     1       AAA    350,00     
 2      bbb       35     3       CCC    100,00

注意：如果你想知道为什么我不将

Orders

与价格相乘：它们没有关系（所以我应该离开这个专栏，因为它有点模棱两可，请忽略它，我只是添加它是为了让一切不那么抽象）。实际上

Orders

必须保持不变，这就是子查询方法加入两者的原因，也是我首先需要分组的原因。

结论：显然，我的问题的核心可以通过

OVER

子句 来回答，它可以应用于 any 聚合函数，如

SUM

（参见 Damien 的回答）这对我来说是新的。谢谢大家的工作方法。

Answer 1

哇，其他答案看起来很复杂——所以我希望我没有遗漏一些明显的东西。

您可以对聚合使用

OVER

/

PARTITION BY

，然后它们将在没有

GROUP BY

子句的情况下进行分组/聚合。所以我只是将您的查询修改为：

select T2.ID AS T2ID
    ,T2.Name as T2Name
    ,T2.Orders
    ,T1.ID AS T1ID
    ,T1.Name As T1Name
    ,T1Sum.Price
FROM @t2 T2
INNER JOIN (
    SELECT Rel.t2ID
        ,Rel.t1ID
 --       ,MAX(Rel.t1ID)AS t1ID 
-- the MAX returns an arbitrary ID, what i need is: 
      ,ROW_NUMBER()OVER(Partition By Rel.t2ID Order By Price DESC)As PriceList
        ,SUM(Price)OVER(PARTITION BY Rel.t2ID) AS Price
        FROM @t1 T1 
        INNER JOIN @relation Rel ON Rel.t1ID=T1.ID
--        GROUP BY Rel.t2ID
)AS T1Sum ON  T1Sum.t2ID = T2.ID
INNER JOIN @t1 T1 ON T1Sum.t1ID=T1.ID
where t1Sum.PriceList = 1

给出请求的结果集。

Answer 2

毫无疑问，这可以简化，但结果符合您的期望。

本文的要点是

• 计算每个

  CTE

  单独

  t2ID
的最高价格
• 为每个

  CTE

  单独计算总价

  t2ID
• 结合

  CTE

  的
的结果

SQL 语句

;WITH MaxPrice AS ( 
    SELECT  t2ID
            , t1ID
    FROM    (       
                SELECT  t2.ID AS t2ID
                        , t1.ID AS t1ID
                        , rn = ROW_NUMBER() OVER (PARTITION BY t2.ID ORDER BY t1.Price DESC)
                FROM    @t1 t1
                        INNER JOIN @relation r ON r.t1ID = t1.ID        
                        INNER JOIN @t2 t2 ON t2.ID = r.t2ID
            ) maxt1
    WHERE   maxt1.rn = 1                            
)
, SumPrice AS (
    SELECT  t2ID = t2.ID
            , Price = SUM(Price)
    FROM    @t1 t1
            INNER JOIN @relation r ON r.t1ID = t1.ID
            INNER JOIN @t2 t2 ON t2.ID = r.t2ID
    GROUP BY
            t2.ID           
)           
SELECT  t2.ID
        , t2.Name
        , t2.Orders
        , mp.t1ID
        , t1.ID
        , t1.Name
        , sp.Price
FROM    @t2 t2
        INNER JOIN MaxPrice mp ON mp.t2ID = t2.ID
        INNER JOIN SumPrice sp ON sp.t2ID = t2.ID
        INNER JOIN @t1 t1 ON t1.ID = mp.t1ID

Answer 3

;with C as
(
  select Rel.t2ID,
         Rel.t1ID,
         t1.Price,
         row_number() over(partition by Rel.t2ID order by t1.Price desc) as rn
  from @t1 as T1
    inner join @relation as Rel
      on T1.ID = Rel.t1ID
)
select T2.ID as T2ID,
       T2.Name as T2Name,
       T2.Orders,
       T1.ID as T1ID,
       T1.Name as T1Name,
       T1Sum.Price
from @t2 as T2
  inner join (
              select C1.t2ID,
                     sum(C1.Price) as Price,
                     C2.t1ID
              from C as C1
                inner join C as C2 
                  on C1.t2ID = C2.t2ID and
                     C2.rn = 1
              group by C1.t2ID, C2.t1ID
             ) as T1Sum
    on T2.ID = T1Sum.t2ID
  inner join @t1 as T1
    on T1.ID = T1Sum.t1ID

Answer 4

重复数据删除（选择最大 T1）和聚合需要作为不同的步骤完成。我使用了 CTE，因为我认为这更清楚：

;WITH sumCTE
AS
(
    SELECT  Rel.t2ID, SUM(Price) price
    FROM    @t1         AS T1
    JOIN    @relation   AS Rel 
    ON      Rel.t1ID=T1.ID
    GROUP 
    BY      Rel.t2ID
)
,maxCTE
AS
(
    SELECT  Rel.t2ID, Rel.t1ID, 
            ROW_NUMBER()OVER(Partition By Rel.t2ID Order By Price DESC)As PriceList
    FROM    @t1         AS T1
    JOIN    @relation   AS Rel 
    ON      Rel.t1ID=T1.ID
)
SELECT T2.ID AS T2ID
,T2.Name as T2Name
,T2.Orders
,T1.ID AS T1ID
,T1.Name As T1Name
,sumT1.Price
FROM    @t2 AS T2
JOIN    sumCTE AS sumT1
ON      sumT1.t2ID = t2.ID
JOIN    maxCTE AS maxT1
ON      maxT1.t2ID = t2.ID
JOIN    @t1 AS T1
ON      T1.ID = maxT1.t1ID
WHERE   maxT1.PriceList = 1