cambia join items i ... a LEFT join items i ... e la tua query dovrebbe funzionare come previsto.
MODIFICA
Non puoi filtrare le tabelle LEFT JOIN nella clausola where a meno che tu non tenga conto dei valori null, perché il join sinistro consente a quelle colonne di avere un valore o essere null quando nessuna riga corrisponde:
and i.siteid = 132 eliminerà tutte le tue righe che hanno un i.siteid NULL , dove non esisteva. Spostalo su ON:
left join items i on ic.itemid = i.itemid and i.siteid = 132
o fai in modo che WHERE gestisca i NULL:
WHERE ... AND (i.siteid = 132 OR i.siteid IS NULL)
MODIFICA in base alla modifica di OP 3
SET NOCOUNT ON
DECLARE @Categories table (CategoryID int,Title varchar(30))
INSERT @Categories VALUES (1,'Cat AAA')
INSERT @Categories VALUES (2,'Cat BBB')
INSERT @Categories VALUES (3,'Cat CCC')
DECLARE @SubCategories table (SubCategoryID int,CategoryID int,Title varchar(30))
INSERT @SubCategories VALUES (1,1,'SubCat AAA A')
INSERT @SubCategories VALUES (2,1,'SubCat AAA B')
INSERT @SubCategories VALUES (3,1,'SubCat AAA C')
INSERT @SubCategories VALUES (4,2,'SubCat BBB A')
DECLARE @ItemCategories table (ItemCategoryID int, ItemID int, SubCategoryID int, IsActive char(1))
INSERT @ItemCategories VALUES (1,1,2,'Y')
INSERT @ItemCategories VALUES (2,2,2,'Y')
INSERT @ItemCategories VALUES (3,3,2,'Y')
INSERT @ItemCategories VALUES (4,4,2,'Y')
INSERT @ItemCategories VALUES (5,7,2,'Y')
DECLARE @Items table (ItemID int, Title varchar(30), SiteID int)
INSERT @Items VALUES (1,'Item A',111)
INSERT @Items VALUES (2,'Item B',111)
INSERT @Items VALUES (3,'Item C',132)
INSERT @Items VALUES (4,'Item D',111)
INSERT @Items VALUES (5,'Item E',111)
INSERT @Items VALUES (6,'Item F',132)
INSERT @Items VALUES (7,'Item G',132)
SET NOCOUNT OFF
Non sono sicuro al 100% di cosa stia cercando l'OP, questo restituirà tutte le informazioni che possono essere unite quando siteid=132 come indicato nella domanda
SELECT
c.title as categorytitle
,s.title as subcategorytitle
,i.title as itemtitle
--,i.itemID, ic.SubCategoryID, s.CategoryID
FROM @Items i
LEFT OUTER JOIN @ItemCategories ic ON i.ItemID=ic.ItemID
LEFT OUTER JOIN @SubCategories s ON ic.SubCategoryID=s.SubCategoryID
LEFT OUTER JOIN @Categories c ON s.CategoryID=c.CategoryID
WHERE i.siteid = 132
USCITA:
categorytitle subcategorytitle itemtitle
------------------------------ ------------------------------ ------------------------------
Cat AAA SubCat AAA B Item C
NULL NULL Item F
Cat AAA SubCat AAA B Item G
(3 row(s) affected)
Questo elencherà tutte le categorie, anche se non c'è corrispondenza con siteid=132
;WITH AllItems AS
(
SELECT
s.CategoryID, ic.SubCategoryID, ItemCategoryID, i.ItemID
,c.title AS categorytitle, s.title as subcategorytitle, i.title as itemtitle
FROM @Items i
LEFT OUTER JOIN @ItemCategories ic ON i.ItemID=ic.ItemID
LEFT OUTER JOIN @SubCategories s ON ic.SubCategoryID=s.SubCategoryID
LEFT OUTER JOIN @Categories c ON s.CategoryID=c.CategoryID
WHERE i.siteid = 132
)
SELECT
categorytitle, subcategorytitle,itemtitle
FROM AllItems
UNION
SELECT
c.Title, s.Title, null
FROM @Categories c
LEFT OUTER JOIN @SubCategories s ON c.CategoryID=s.CategoryID
LEFT OUTER JOIN @ItemCategories ic ON s.SubCategoryID=ic.SubCategoryID
LEFT OUTER JOIN AllItems i ON c.CategoryID=i.CategoryID AND s.SubCategoryID=i.SubCategoryID
WHERE i.ItemID IS NULL
ORDER BY categorytitle,subcategorytitle
USCITA:
categorytitle subcategorytitle itemtitle
------------------------------ ------------------------------ ------------------------------
NULL NULL Item F
Cat AAA SubCat AAA A NULL
Cat AAA SubCat AAA B Item C
Cat AAA SubCat AAA B Item G
Cat AAA SubCat AAA C NULL
Cat BBB SubCat BBB A NULL
Cat CCC NULL NULL
(7 row(s) affected)
