如何使用 window 函数获取最高价格及其 ID？

Question

我有这个问题

select adate, factoryid, purchid, itemname, max(price) as price 
from tableb where catnum = 9
group by adate, factoryid, purchid, itemname
order by adate, factoryid, purchid, itemname

但我想要该行的 ID。所以在一个完美的世界里：

select id, adate, factoryid, purchid, itemname, max(price) as price 
from tableb where catnum = 9
group by adate, factoryid, purchid, itemname
order by adate, factoryid, purchid, itemname

但我知道这行不通。

所以我尝试了这个：

select id, adate, factoryid, purchid, itemname, 
       max(price) over(partition by adate, factoryid, purchid, itemname) as price 
from tableb where catnum = 9

那是行不通的。所有 ID 的价格都是重复的。查询结果集从 4000 行增加到 11000 行。

很明显，我把 window 函数弄错了。首先，我做错了什么，其次，当然，我该如何解决？

Answer 1

SELECT  *
FROM    (
        SELECT  *,
                ROW_NUMBER() OVER (PARTITION BY adate, factoryid, purchid, itemname ORDER BY price DESC, id DESC) rn
        FROM    tableb 
        WHERE   catnum = 9
        ) q
WHERE   rn = 1

Answer 2

我不太清楚你为什么要这个 id 但是... 假设

您需要条件的所有 ID
id是tableb的PK

那么这可能有效：

SELECT tableb.* FROM tableb
INNER JOIN
(
select adate, factoryid, purchid, itemname, max(price) as price 
from tableb where catnum = 9
group by adate, factoryid, purchid, itemname
) AS grouped
ON  tableb.adate = grouped.adate AND
    tableb.factoryid = grouped.factoryid AND
    tableb.purchid = grouped.purchid AND
    tableb.itemname = grouped.itemname AND
    tableb.price = grouped.price
order by tableb.adate, tableb.factoryid, tableb.purchid, tableb.itemname

Answer 3

您可以将 MAX 的窗口版本与 FIRST_VALUE 一起使用，可从 SQL Server 2012+ 获得：

SELECT DISTINCT adate, factoryid, purchid, itemname, 
       MAX(price) OVER (PARTITION BY adate, factoryid, purchid, itemname) AS price,
       FIRST_VALUE(id) OVER (PARTITION BY adate, factoryid, purchid, itemname
                             ORDER BY price DESC) AS id
FROM tableb 
WHERE catnum = 9
ORDER BY adate, factoryid, purchid, itemname

如何使用 window 函数获取最高价格及其 ID？

How do I use window function to get max price and its id?

sql

tsql

aggregate-functions

window-functions

sql-server-2012