使用链接的服务器变量将查询转换为动态SQL [英] Converting a query to dynamic SQL with linked server variable

问题描述

我有一个需要转换的存储过程，以便它从表中读取链接的服务器变量。据我所知，唯一的方法是使用动态SQL。问题是我无法转换查询。

I have a stored procedure that I need to convert so that it reads a linked server variable from a table. From what I know, the only way to do so is to use dynamic SQL. The problem is that I'm failing to convert my query.

原始查询：

SET @var1 = ''
SELECT  @var1 = RECEIVER        
FROM    databse1.dbo.table1 
WHERE   SAPNUMBER = @var2

转换后的查询：

SET @srv = (SELECT server_name
            FROM Configuration.dbo.Server_Switch)

SET @var1 = ''
exec (  
'SELECT ' + @var1 + '= RECEIVER
FROM ' + @srv + '.databse1.dbo.table1 
WHERE SAPNUMBER =' + @var2
)

我得到的错误是：

Incorrect syntax near '='

@ var1和@ var2是事先声明的变量。我敢肯定，在动态SQL中为这些变量分配值时会出现问题，因此会出现 =错误。我可以在转换此查询方面获得帮助吗？

@var1 and @var2 are variables declared beforehand. I'm pretty sure there's a problem in assigning values to these variables in dynamic SQL, hence the '=' error. Can I get some help in converting this query?

推荐答案

一种解决方法是使用带有输出参数的sp_executeSql：

One way to solve it is to use sp_executeSql with an output parameter:

SET @srv = (SELECT server_name
            FROM Configuration.dbo.Server_Switch)

DECLARE @sql nvarchar(500),
        @ParmDefinition nvarchar(500);

SET @sql = 
'SELECT @output = RECEIVER
FROM ' + @srv + '.databse1.dbo.table1 
WHERE SAPNUMBER =' + @var2

SET @ParmDefinition = N'@var1 varchar(100) OUTPUT';

EXEC sp_executesql @Sql, @ParmDefinition, @var1=@output OUTPUT;

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