不能在SQL Server 2008上绑定多部分标识符 [英] The multi-part identifier could not be bound on SQL Server 2008

问题描述

我有2张桌子

requests(ID，company_id，amount)

companies(ID，name)

受FK约束(requests.company_id-> companies.id)

requests.company可以是NULL

我需要获取所有请求，并用相应的公司name替换company_id，如果未指定公司，则将其留空.

I need to get all requests and replace company_id with appropriated company name or left it blank if no company was specified.

我有下一个查询:

SELECT R.[ID], C.[name] AS [company], R.[amount], ...
FROM [requests] AS R, [companies] AS C, ...
WHERE R.[company_id] = C.[ID]

并且可以正常工作，直到company字段为NULL.

and it's working fine until a NULL into company field.

我尝试下一步:

SELECT R.[ID], C.[name] AS [company], ...
FROM [requests] AS R, ...
LEFT OUTER JOIN [companies] AS C
ON R.[company_id] = S.ID

但是得到了

无法绑定多部分标识符"R.company_id"

The multi-part identifier "R.company_id" could not be bound

和ON子句移动中的字段上的相同错误.我在做什么错了?

And the same errors on fields in ON clause shifting. What am I doing wrong?

推荐答案

您显示的代码示例带有省略号，并且我相信是引起问题的椭圆中的原因.

The code example you showed had ellipses and I believe it is what is in the ellipses that are causing the trouble.

您有:

SELECT R.[ID], C.[name] AS [company], ...
FROM [requests] AS R, ...
LEFT OUTER JOIN [companies] AS C
ON R.[company_id] = S.ID

比方说:

SELECT R.[ID], C.[name] AS [company], X.Field
FROM [requests] AS R, [eXample] as X 
LEFT OUTER JOIN [companies] AS C
ON R.[company_id] = S.ID
WHERE X.[request_id] = R.ID

换句话说，将ANSI 92以前的内部联接语法与ANSI 92外部联接语法混合在一起.在SQL Server 2005上进行测试，在您的示例中，似乎似乎看不到将请求R和...分隔开逗号的逗号，并且[eXample]在我的X中看不到.但是，以下方法确实起作用:

In other words the mixing of pre-ANSI 92 inner join syntax with ANSI 92 outer join syntax. Testing on SQL Server 2005, it appears that the alias R for requests is not seen past the comma that separates R from ... in your example, and [eXample] as X in mine. The following however did work:

SELECT R.[ID], C.[name] AS [company], X.Field
FROM [eXample] as X, [requests] AS R 
-- Requests and companies on the same side of the comma
LEFT OUTER JOIN [companies] AS C
ON R.[company_id] = S.ID
WHERE X.[request_id] = R.ID

或

SELECT R.[ID], C.[name] AS [company], X.Field
FROM [requests] AS R LEFT OUTER JOIN [companies] AS C
    ON R.[company_id] = S.ID, [eXample] as X 
WHERE X.[request_id] = R.ID
-- Yuck, I would hate to find this. Not at all sure from reading
-- the code how it would work.

或我最喜欢的，因为我喜欢ANSI 92连接语法:

or my favorite, because I like ANSI 92 join syntax:

SELECT R.[ID], C.[name] AS [company], X.Field
FROM [requests] AS R
INNER JOIN [eXample] as X ON X.[request_id] = R.ID
LEFT OUTER JOIN [companies] AS C ON R.[company_id] = S.ID

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