如何根据两个参数连接两个以上的表？答案

【问题标题】：How to join more than two tables on the basis of two parameters?如何根据两个参数连接两个以上的表？
【发布时间】：2015-01-15 06:38:14
【问题描述】：

我有三个表#temp、tbProducts 和tbVendor

tbVendor(States, AgentId, Products)

tbProduct(ProductId, ProductName)

#temp(ProductName)

样本数据

tbVendor
-------------------------------- ----------- --------------------
States                           AgentId     Products
-------------------------------- ----------- --------------------
Alabama,New York                 1           T.V, Desktops
New Jersy, Florida               2           Cellphones, Laptops
New York, San Fransico           1           Cellphones, Desktop
New Jersy, San Fransico          1           A.C, Heaters

tbProduct
----------- -------------
ProductId   ProductName
----------- -------------
1           T.V
2           Laptops
3           Desktop
4           Cellphones
5           A.C
6           Heaters

#temp
---------------
ProductName
---------------
T.V
Laptops
Desktop
Cellphones
A.C
Heaters

现在我已经对它们执行连接操作以获取 ProductId 和 ProductName
在Agent Id 和States 字段的基础上分配tbVendor。

例如，我在New york 和AgentId = 1 中获取了所有Products 和Names 和Ids，输出应该是这样的

ProductId   ProductName
----------- -------------
1           T.V
3           Desktop
4           Cellphones

请注意，#Temp 包含分配给AgentId = 1 的所有产品。不知何故，我设法获取分配给AgentId = 1 的所有产品，并将它们放在#temp 表中。现在我无法设法获取输出，例如仅分配给New York 的产品预期输出如下所示

ProductId   ProductName
----------- -------------
1           T.V
3           Desktop
4           Cellphones

我试过下面的代码行它不起作用

Select * from tbProduct L
JOIN #Temp TL  ON L.ProductName collate SQL_Latin1_General_CP1_CI_AS = TL.ProductName
JOIN tbVendor Li ON Li.AgentId = @AgentId and Li.States like @States;

注意@States 包含New York 和@AgentId 包含1。

【问题讨论】：

你不能重新设计数据库shema吗？目前，您有状态和产品的逗号分隔列表 - 这使得任何连接都非常困难（您必须使用字符串操作）并且无效。
我知道这个逗号造成了很多麻烦......但我没有设计这个架构......如果我这样做，我必须重新工作多年的工作由其他开发者完成。完成整个项目需要很长时间...请帮助我
tbVendor 的结构违反了 First NF，需要规范化。您将逗号分隔的列表存储在一列中，这有很多缺点。例如，您将无法存储比列中适合的列表更长的列表。编辑：好的，现在我明白了..
您能否在问题中包含预期输出的示例？
检查上面的问题...我已经标记了预期的输出

标签： sql sql-server sql-server-2008 join

【解决方案1】：

写成：

;WITH cte AS (
    SELECT 
        AgentId,
        CAST('<r>' + REPLACE(States, ',', '</r><r>') + '</r>' AS XML) AS States,
        CAST('<r>' + REPLACE(Products, ',', '</r><r>') + '</r>' AS XML) AS Products
    FROM @tbVendor
)
,FinalList AS (
SELECT 
    AgentId,
    RTRIM(LTRIM (sTable.sColumn.value('.', 'VARCHAR(MAX)'))) AS States,
    RTRIM(LTRIM (PTable.PColumn.value('.', 'VARCHAR(MAX)'))) AS Products
FROM cte
CROSS APPLY States.nodes('//r') AS sTable(sColumn) 
CROSS APPLY Products.nodes('//r') AS PTable(PColumn) 
)
SELECT DISTINCT F.Products AS ProductName
       ,T.ProductId AS ProductId       
FROM FinalList F
CROSS APPLY (SELECT ProductId FROM @tbProduct TP WHERE TP.ProductName = F.Products) AS T
WHERE F.States = 'New York'
AND F.AgentId = 1
ORDER BY T.ProductId ASC

更新：处理特殊字符 LIKE &amp; 将其替换为 &amp; 为：

;WITH cte AS (
    SELECT 
        AgentId,
        CAST('<r>' + REPLACE(States, ',', '</r><r>') + '</r>' AS XML) AS States,
        CAST('<r>' + REPLACE(REPLACE(Products,'&','&amp;'), ',', '</r><r>') + '</r>' AS XML) AS Products
    FROM @tbVendor
)
,FinalList AS (
SELECT 
    AgentId,
    RTRIM(LTRIM (sTable.sColumn.value('.', 'VARCHAR(MAX)'))) AS States,
    RTRIM(LTRIM (PTable.PColumn.value('.', 'VARCHAR(MAX)'))) AS Products
FROM cte
CROSS APPLY States.nodes('//r') AS sTable(sColumn) 
CROSS APPLY Products.nodes('//r') AS PTable(PColumn) 
)
SELECT DISTINCT F.Products AS ProductName
       ,T.ProductId AS ProductId       
FROM FinalList F
CROSS APPLY (SELECT ProductId FROM @tbProduct TP WHERE TP.ProductName = F.Products) AS T
WHERE F.States = 'New York'
AND F.AgentId = 1
ORDER BY T.ProductId ASC

DEMO

【讨论】：

伟大的努力......它工作正常，但有一些产品保存为美容和护肤品，它正在抛出 XML 解析：第 1 行，字符 100，此类产品的非法名称字符错误消息
您必须将 & 替换为 &amp，就像其他特殊字符一样，您也必须先替换 ..
非常感谢先生...非常感谢您的回答是出色的解决方案
这个'-'字符怎么样，对不起，我忘了提

【解决方案2】：

试试这个：

DECLARE @state varchar(25) = 'New York',
@agentId int = 1

SELECT STUFF((SELECT ', ' + Products 
        FROM tbVendor tv 
        WHERE tv.AgentId = @agentId AND tv.States Like  '%' +@state + '%'
        FOR XML PATH('')), 1, 2, '') AS products
INTO #tmp

;with tmp(product, products) as (
select  LTRIM(LEFT(products, CHARINDEX(', ',products+', ')-1)),
    STUFF(products, 1, CHARINDEX(', ',products+', '), '')
from #tmp
union all
select  LTRIM(LEFT(products, CHARINDEX(', ',products+', ')-1)),
    STUFF(products, 1, CHARINDEX(', ',products+', '), '')
from tmp
where products > ''
)
SELECT tp.*
FROM tbProduct tp
INNER JOIN tmp t ON t.product = tp.ProductName

【讨论】：

【解决方案3】：

将 CSV 拆分为行

;WITH CTE AS
(   
    -- Split States
    SELECT ROW_NUMBER() OVER(ORDER BY (SELECT(0))) RNO, 
    AgentId,
    LTRIM(RTRIM(Split.a.value('.', 'VARCHAR(100)'))) 'STATE'    
    FROM  
    (
         -- Use 3 REPLACE for  '|', ';', ','
         SELECT AgentId,
         CAST ('<M>' + REPLACE([STATE], ',', '</M><M>') + '</M>' AS XML) AS Data         
         FROM #tbVendor

    ) AS A 
    CROSS APPLY Data.nodes ('/M') AS Split(a)
)   
SELECT C1.AGENTID,C1.[STATE],TAB.Products,P.ProductID     
FROM CTE C1
JOIN
(   
    -- Split Products
    SELECT ROW_NUMBER() OVER(ORDER BY (SELECT(0))) RNO, AgentId,
    LTRIM(RTRIM(Split.A.value('.', 'VARCHAR(100)'))) 'Products' 
    FROM  
    (
         -- Use 3 REPLACE for  '|', ';', ','
         SELECT AgentId,         
         CAST ('<M>' + REPLACE(Products, ',', '</M><M>') + '</M>' AS XML) AS Data      
         FROM #tbVendor

    ) AS A 
    CROSS APPLY Data.nodes ('/M') AS Split(a)
)TAB
ON C1.RNO=TAB.RNO AND C1.AGENTID=TAB.AGENTID
-- Get Product Id
JOIN #tbProduct P
ON TAB.Products=P.ProductName
WHERE ...your conditions...

现在您将获得所有states 和ProductId、ProductName 和AgentId

SQL FIDDLE

【讨论】：