Converting a query to dynamic SQL with linked server variable

问题

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.

Original query:

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

Converted query:

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

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

The error that I'm getting is:

Incorrect syntax near '='

@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?

回答1:

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;

回答2:

Please provide more info. We need variables @var2, @var1 declaration, types of variables. If @var2 is varchar, then please update your query in followoing way:

declare @sql nvarchar(4000) = 
'SELECT ' + @var1 + '= RECEIVER
FROM ' + @srv + '.databse1.dbo.table1 
WHERE SAPNUMBER =' + char(39) + @var2 + char(39);

exec(@sql);

P.S. if @var2 numeric:

declare @sql nvarchar(4000) = 
'SELECT ' + @var1 + '= RECEIVER
FROM ' + @srv + '.databse1.dbo.table1 
WHERE SAPNUMBER =' + @var2;
exec(@sql);

来源：https://stackoverflow.com/questions/41743049/converting-a-query-to-dynamic-sql-with-linked-server-variable

标签

sql-server

variables

server

dynamic-sql