Question

我有这个查询

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

但我想要那一行的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

但我知道这不行。

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

这不起作用。所有ID的价格都是重复的。查询结果集从4000行变为11000。

很明显，我以某种方式弄错了窗口功能。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

您可以使用MAX的窗口版本以及FIRST_VALUE，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

Answer 3

我不清楚你为什么要这个id但是...... 假设

你想要条件的所有ID
id是tableb的PK

然后这可能会起作用：

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

如何使用窗口函数获取最大价格及其ID？

3 个答案: