我有以下查询，它查找与搜索匹配的前 5 个产品。每个产品都与一个商店
相关联从产品中选择 TOP 5 * p, 商店 s WHERE p.ShopId = s.ShopId 和 p.ProductName 喜欢 '%christmas%'
我需要扩展它，以便它返回我 每个 Shop 中的 TOP 5 Products。
谁能告诉我如何修改查询来实现这一点？ - 即选择 每个 商店中匹配“%christmas%”的 TOP 5 产品（而不是当前显示在 所有 商店中匹配“%chrismas%”的 TOP 5 产品)。
【问题讨论】：
标签： sql-server greatest-n-per-group
您实际上缺少一个 ORDER BY 以使 TOP 有意义，或者任何基于 ROW_NUMBER 的解决方案都需要一个 ORDER BY。
SELECT
*
FROM
Shops s
CROSS APPLY (
SELECT TOP 5
*
FROM
Products p
WHERE
p.ShopId = s.ShopId AND p.ProductName LIKE '%christmas%'
ORDER BY --added on edit
???
) X
【讨论】：
试试这个：
select * from (
select *, rn = row_number() over (partition by s.ShopId order by p.ProductName)
from Products p, Shops s
where p.ShopId = s.ShopId AND p.ProductName LIKE '%christmas%'
) a where a.rn <= 5
【讨论】：
试试这个
SELECT DISTINCT
A.Product_Group_code
,B.Sub_Product_Group_code
,A.Product_code
,A.Product_name
FROM dbo.A A
LEFT JOIN dbo.B B
ON A.Product_code = B.Product_code
WHERE B.Product_code IN
(
SELECT TOP 5 E.Product_code
FROM dbo.A D
LEFT JOIN dbo.B E
ON D.Product_code = E.Product_code
WHERE E.Sub_Product_Group_code = B.Sub_Product_Group_code
)
AND B.Sub_Product_Group_code IS NOT NULL
ORDER BY B.Sub_Product_Group_code,A.Product_name
【讨论】：
这是我刚刚找到的一个很好的解决方案。
为每个组选择前 n 行 阿尼罗兰，2008 年 3 月 13 日
每个类别有多个行，并且希望 按价格仅选择每个类别的前两 (2) 行。 例如，从以下数据：
RowID Category ID Description Price
1 Pot A1 Small Saucepan 21.50
2 Pot A2 1 Qt Saucepan 29.95
3 Pot A3 1.5 Qt Saucepan 33.95
4 Pot A4 Double Boiler 39.50
5 Pot A5 Stewpot 49.50
6 Pot A6 Pressure Cooker 79.95
7 Pan B1 8" Pie 6.95
8 Pan B2 8" Sq Cake 7.50
9 Pan B3 Bundt Cake 12.50
10 Pan B4 9x12 Brownie 7.95
11 Bowl C1 Lg Mixing 27.50
12 Bowl C2 Sm Mixing 17.50
13 Tools T1 14" Spatula 9.95
想要的输出是：
RowID Category ID Description Price
11 Bowl C1 Lg Mixing 27.50
12 Bowl C2 Sm Mixing 17.50
9 Pan B3 Bundt Cake 12.50
10 Pan B4 9x12 Brownie 7.95
6 Pot A6 Pressure Cooker 79.95
5 Pot A5 Stewpot 49.50
13 Tools T1 14" Spatula 9.95
有几种方法可以实现所需的输出。 该演示提供了 SQL Server 2005 / SQL Server 2008 的解决方案， 然后是 SQL Server 2000 的解决方案。
为两种解决方案创建示例数据
-- Suppress data loading messages
SET NOCOUNT ON
-- Create Sample Data using a Table Varable
DECLARE @MyTable table
( RowID int IDENTITY,
Category varchar(5),
[ID] varchar(5),
[Description] varchar(25),
Price decimal(10,2)
)
-- Load Sample Data
INSERT INTO @MyTable VALUES ( 'Pot', 'A1', 'Small Saucepan', 21.50 )
INSERT INTO @MyTable VALUES ( 'Pot', 'A2', '1 Qt Saucepan', 29.95 )
INSERT INTO @MyTable VALUES ( 'Pot', 'A3', '1.5 Qt Saucepan', 33.95 )
INSERT INTO @MyTable VALUES ( 'Pot', 'A4', 'Double Boiler', 39.50 )
INSERT INTO @MyTable VALUES ( 'Pot', 'A5', 'Stewpot', 49.50 )
INSERT INTO @MyTable VALUES ( 'Pot', 'A6', 'Pressure Cooker', 79.95 )
INSERT INTO @MyTable VALUES ( 'Pan', 'B1', '8"" Pie', 6.95 )
INSERT INTO @MyTable VALUES ( 'Pan', 'B2', '8"" Sq Cake', 7.50 )
INSERT INTO @MyTable VALUES ( 'Pan', 'B3', 'Bundt Cake', 12.50 )
INSERT INTO @MyTable VALUES ( 'Pan', 'B4', '9x12 Brownie', 7.95 )
INSERT INTO @MyTable VALUES ( 'Bowl', 'C1', 'Lg Mixing', 27.50 )
INSERT INTO @MyTable VALUES ( 'Bowl', 'C2', 'Sm Mixing', 17.50 )
INSERT INTO @MyTable VALUES ( 'Tools', 'T1', '14"" Spatula', 9.95 )
Return to Top
SQL Server 2005 / SQL Server 2008 解决方案
--Query to Retrieve Desired Data
SELECT
RowID,
Category,
[ID],
[Description],
Price
FROM (SELECT
ROW_NUMBER() OVER ( PARTITION BY Category ORDER BY Price DESC ) AS 'RowNumber',
RowID,
Category,
[ID],
[Description],
Price
FROM @MyTable
) dt
WHERE RowNumber <= 2
-- Results
RowID Category ID Description Price
11 Bowl C1 Lg Mixing 27.50
12 Bowl C2 Sm Mixing 17.50
9 Pan B3 Bundt Cake 12.50
10 Pan B4 9x12 Brownie 7.95
6 Pot A6 Pressure Cooker 79.95
5 Pot A5 Stewpot 49.50
13 Tools T1 14" Spatula 9.95
Return to Top
使用 CTE 的 SQL Server 2005 / SQL Server 2008 解决方案 （添加：雅各布·塞巴斯蒂安）
-- Define a CTE with the name "dt"
;WITH dt AS (
SELECT
ROW_NUMBER() OVER ( PARTITION BY Category ORDER BY Price DESC ) AS 'RowNumber',
RowID,
Category,
[ID],
[Description],
Price
FROM @MyTable
)
-- and select the data from the CTE
SELECT
RowID,
Category,
[ID],
[Description],
Price
FROM dt
WHERE RowNumber <= 2
-- Results
RowID Category ID Description Price
11 Bowl C1 Lg Mixing 27.50
12 Bowl C2 Sm Mixing 17.50
9 Pan B3 Bundt Cake 12.50
10 Pan B4 9x12 Brownie 7.95
6 Pot A6 Pressure Cooker 79.95
5 Pot A5 Stewpot 49.50
13 Tools T1 14" Spatula 9.95
Return to Top
SQL 2000 解决方案
--Query to Retrieve Desired Data
SELECT DISTINCT
RowID,
Category,
[ID],
[Description],
Price
FROM @MyTable t1
WHERE RowID IN (SELECT TOP 2
RowID
FROM @MyTable t2
WHERE t2.Category = t1.Category
ORDER BY Price DESC
)
ORDER BY
Category,
Price DESC
-- Results
RowID Category ID Description Price
11 Bowl C1 Lg Mixing 27.50
12 Bowl C2 Sm Mixing 17.50
9 Pan B3 Bundt Cake 12.50
10 Pan B4 9x12 Brownie 7.95
6 Pot A6 Pressure Cooker 79.95
5 Pot A5 Stewpot 49.50
13 Tools T1 14" Spatula 9.95
【讨论】：