Question

我有下表：

Item           Prod        Company
1.00961.501    PR011798    ditto
1.00961.501    PR012042    ditto
1.00961.501    PR013442    Pika
1.00961.502    PR012043    ditto
1.00961.503    PR011959    ditto
1.00961.503    PR011669    Bulb
1.00961.507    PR014783    ditto
1.00961.507    PR012050    ditto

我想选择按Item分组的所有表，仅使用最大Prod。像这样：

Item           Prod        Company
1.00961.501    PR012042    ditto
1.00961.502    PR012043    ditto
1.00961.503    PR011959    ditto
1.00961.507    PR014783    ditto

我尝试了以下操作：

SELECT  DISTINCT Item, MAX(Prod)
FROM    DataBase
WHERE   Company = 'ditto'

但这给了我

Column 'Item' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.

如果我删除了MAX条款，则不会返回任何错误，但是Item对每个Prod都会重复。

有什么想法吗？

编辑

我忘了在问题中添加Where子句。当我这样做时，尝试使用Group By而不是Distinct时出现以下错误：

Column 'Company' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.

Answer 1

您的查询应该是这样；

SELECT  Item, MAX(Prod),Company
FROM    DataBase
WHERE   Company = 'ditto'
GROUP BY Item,Company;

Answer 2

您需要对产品进行分区，然后从该分区中选择一个。

您应该在下面的查询中尝试使用此方法。

  select Item, Prod, Company from 
  (
    select *,
    (ROW_NUMBER() over (partition by Item order by Prod DESC)) as Row from [table_name] 
    where Company = 'ditto'
  ) t where Row = 1

按第一列和第二列的最大值选择不同的行

编辑

2 个答案: