Select 在 SQL 服务器中只有 max(id) 行

Question

我有一张表 A：

ID     | ProductCatId | ProductCode | Price
1      |       1      |  PROD0001   | 2
2      |       2      |  PROD0005   | 2
3      |       2      |  PROD0005   | 2
4      |       3      |  PROD0008   | 2
5      |       5      |  PROD0009   | 2
6      |       7      |  PROD0012   | 2

我想要 select ID,ProductCatId,ProductCode,Price 条件： “如果 ProductCatId 存在相同的值，那么使用 max(ID) 获取 ProductCatId” ，例如：

ID     | ProductCatId | ProductCode | Price
1      |       1      |  PROD0001   | 2
3      |       2      |  PROD0005   | 2
4      |       3      |  PROD0008   | 2
5      |       5      |  PROD0009   | 2
6      |       7      |  PROD0012   | 2

Answer 1

转到窗口函数和row_number（）

select ID , ProductCatId , ProductCode , Price
  from (
        select ID , ProductCatId , ProductCode , Price, row_number() over (partition by ProductCatId order by ID desc) as rn
         from myTable
        ) as t
  where t.rn = 1

Answer 2

你可以试试看

Select Max(ID),ProductCatId,ProductCode,price
From TableName
Group By ProductCatId,ProductCode,price

Answer 3

select 
top 1 with ties
ID,ProductCatId,ProductCode,Price
from
table
order by
row_number() over (partition by productcatid order by id desc)

Answer 4

可以使用row_number() ：

select t.*
from (select t.*,
             row_number() over (partition by ProductCatId order by ID desc) as seqnum
      from @Table t
     ) t
where seqnum = 1
order by ID;

Answer 5

短一点：

SELECT DISTINCT 
    max(ID) OVER (PARTITION BY ProductCatId, 
                               ProductCode, 
                               Price) AS ID,
    ProductCatId, 
    ProductCode, 
    Price,
  FROM myTable