Question

我有三列的表（交易者，产品，价格）。我想让每个交易者一次和产品以最高价格交易该交易者。当我选择以下时，我会看到重复的交易者：

select Trader, Product, Max(Price) as Price
from dbo.Sell
group by Trader, Product 
order by Max(Price) desc

上述查询的独特交易者如何？下面的查询不会改变任何内容：

select distinct Trader, Product, Max(Price) as Price
from dbo.Sell
group by Trader, Product 
order by Max(Price) desc

实际上，以下查询几乎是我想要的，但是我希望看到Product而不是Price。

select Trader, Max(Price) as Price
from dbo.Sell
group by Trader

Answer 1

尝试此查询，只有当交易者拥有多个具有最高价格的产品时，您才会获得多条记录。

;with cte as (
    select Trader, Max(Price) as Price
    from dbo.Sell
    group by Trader
)
select cte.Trader, s.Product, cte.Price
from cte join dbo.Sell s
         on cte.Trader = s.Trader and cte.Price = s.Price
order by cte.Price desc

第二种方法是使用rank()函数，但rank（）函数将为相同的价格记录带来多条记录。

要获得单个记录，您可以使用Row_Number()代替Rank()。

;with cte as (
    select Trader, Product, Price, 
         Rank() over (partition by Trader order by Price desc) rnk
    from dbo.Sell

)
Select Trader, Product, Price 
From cte
Where rnk = 1
Order by Price desc

分组，顺序，分开

1 个答案: