选择所有类别中包含的产品

Question

我的Product记录使用ProductCategory表与多对多记录到Category记录。

在存储过程中，我有两个或更多CategoryId值的列表（CategoryIds）。如何查询Product表并仅返回与CategoryIds中的类别相关的产品？我无法弄清楚我是否需​​要加入或选择或..？

 
SELECT 
    * 
FROM 
    Product as P 
    -- I can't join here because the relation is many-to-many 
WHERE 
    -- This only checks if there is one category to which the product is related 
    (SELECT Count(C.CategoryId) FROM ProductCategory as PC INNER JOIN Category as C ON PC.CategoryId = C.CategoryId WHERE PC.ProductId = P.ProductId AND PC.CategoryId IN (@CategoryIds)) > 0 

任何帮助，非常感谢！

Answer 1

下面的语句将返回你所有的产品在CSV参数类别规定：

DECLARE @Products TABLE 
(
    [ProductID] INT 
    ,[ProductName] NVARCHAR(32) 
) 

DECLARE @Categories TABLE 
(
    [CategoryID] INT 
    ,[CategotyName] NVARCHAR(32) 
) 

DECLARE @ProductCategory TABLE 
(
    [ProductID] INT 
    ,[CategoryID] INT 
) 


INSERT INTO @Products ([ProductID], [ProductName]) 
VALUES (1, 'Product 1') 
     ,(2, 'Product 2') 
     ,(3, 'Product 3') 
     ,(4, 'Product 4') 

INSERT INTO @Categories ([CategoryID], [CategotyName]) 
VALUES (1, 'Category 1') 
     ,(2, 'Category 2') 
     ,(3, 'Category 3') 

INSERT INTO @ProductCategory ([ProductID], [CategoryID]) 
VALUES (1, 1) 
     ,(1, 2) 
     ,(1, 3) 
     ,(2, 1) 
     ,(2, 2) 
     ,(3, 1) 
     ,(4, 2) 
     ,(4, 3) 

DECLARE @CategoriesCSV NVARCHAR(MAX) = '1,2' 


DECLARE @CategoriesXML XML = N'<r><![CDATA[' + REPLACE(@CategoriesCSV, ',', ']]></r><r><![CDATA[') + ']]></r>' 

;WITH DataSource AS 
(
    SELECT DISTINCT CAST(Tbl.Col.value('.', 'float') AS BIGINT) AS [CategoryID] 
    FROM @CategoriesXML.nodes('//r') Tbl(Col) 
    WHERE ISNUMERIC(Tbl.Col.value('.', 'varchar(max)')) = 1 
) 
SELECT C.[CategoryID] 
     ,C.[CategotyName] 
     ,P.[ProductID] 
     ,P.[ProductName] 
FROM @Categories C 
INNER JOIN DataSource DS 
    ON C.[CategoryID] = DS.[CategoryID] 
INNER JOIN @ProductCategory PC 
    ON C.[CategoryID] = PC.[CategoryID] 
INNER JOIN @Products P 
    ON PC.[ProductID] = P.[ProductID] 

从上面的查询结果是：