Voici une façon.
En théorie, il peut gérer jusqu'à 20 balises par produit (limité par la taille du tableau des nombres), mais je n'ai pas pris la peine d'essayer cela. Sur mon bureau, il a fallu environ 30 secondes pour produire les 65 535 résultats pour un seul produit avec 16 balises. Espérons que votre nombre réel de balises par produit sera bien inférieur à cela !
IF OBJECT_ID('tempdb..#Nums') IS NULL
BEGIN
CREATE TABLE #Nums
(
i int primary key
)
;WITH
L0 AS (SELECT 1 AS c UNION ALL SELECT 1),
L1 AS (SELECT 1 AS c FROM L0 A CROSS JOIN L0 B),
L2 AS (SELECT 1 AS c FROM L1 A CROSS JOIN L1 B),
L3 AS (SELECT 1 AS c FROM L2 A CROSS JOIN L2 B),
L4 AS (SELECT 1 AS c FROM L3 A CROSS JOIN L3 B),
L5 AS (SELECT 1 AS c FROM L4 A CROSS JOIN L4 B),
Nums AS (SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) AS i FROM L5)
INSERT INTO #Nums
SELECT TOP 1048576 i FROM Nums;
END
;with ProductTags As
(
SELECT 1 ProductId,'Leather' AS Tag UNION ALL
SELECT 1, 'Watch' UNION ALL
SELECT 2, 'Red' UNION ALL
SELECT 2, 'Necklace' UNION ALL
SELECT 2, 'Pearl'
), NumberedTags AS
(
SELECT
ProductId,Tag,
ROW_NUMBER() OVER (PARTITION BY ProductId ORDER BY Tag) rn,
COUNT(*) OVER (PARTITION BY ProductId) cn
FROM ProductTags
),
GroupedTags As
(
SELECT ProductId,Tag,i
FROM NumberedTags
JOIN #Nums on
#Nums.i < POWER ( 2 ,cn)
and #Nums.i & POWER ( 2 ,rn-1) > 0
)
SELECT ProductId,
STUFF((SELECT CAST(', ' + Tag AS VARCHAR(MAX))
FROM GroupedTags g2
WHERE g1.ProductId = g2.ProductId and g1.i = g2.i
ORDER BY Tag
FOR XML PATH ('')),1,1,'') AS Tags
FROM GroupedTags g1
GROUP BY ProductId, i
ORDER BY ProductId, i
Retours
ProductId Tags
----------- ------------------------------
1 Leather
1 Watch
1 Leather, Watch
2 Necklace
2 Pearl
2 Necklace, Pearl
2 Red
2 Necklace, Red
2 Pearl, Red
2 Necklace, Pearl, Red
