SQL Server OPENQUERY中包含Bracketed标识符的问题

Question

Not sure, if this should go on Stack Overflow, or the DBA section.

Having an issue with a procedure I'm writing. I have a variable, lets say:

SET @name sysname --also tried to make as varchar

This is used inside a cursor, and will basically contain SQL Server names. Several of the server names are followed by instances names. For example

DECLARE @name = 'SERVER1\INSTANCE1'

Inside the cursor, I have this query.

SELECT @name, * FROM OPENQUERY(@name,
                      'SELECT 
                            i.Name, 
                            i.database_id, 
                            b.mirroring_state 

                            FROM msdb.sys.databases i
                            INNER JOIN msdb.sys.database_mirroring b
                            ON i.database_id = b.database_id
                            WHERE b.mirroring_state IS NOT NULL')

which doesn't work because of the \\ inside the @name

However, if I try this, it works perfectly.

SELECT 'SERVER1\INSTANCE1', * FROM OPENQUERY([SERVER1\INSTANCE1],

The issue I'm having is trying to use the bracketed identifier with the @name inside the OPENQUERY.

I have tried several things, including various combinations of OPENQUERY('['+@name+']',

If you just try FROM OPENQUERY([@name], SQL Server parses it literally as @name.

Any ideas on how to use the servername\\instance name without having these issues?

Edit, full section of the code:

 DECLARE @name sysname,
        @sql nvarchar(4000)

 DECLARE c1 CURSOR FOR 
                SELECT SUBSTRING (Servername, 2, LEN(Servername)-2) 
                FROM AllServers
OPEN c1
    FETCH NEXT FROM c1
    INTO @name
    WHILE @@FETCH_STATUS = 0
    BEGIN

            set @sql = 'INSERT INTO MirrorResults
                            SELECT ''[' + @name + ']'', * FROM OPENQUERY([' + @name + '], 
                                ''
                                SELECT 
                                    i.Name, 
                                    i.database_id, 
                                    b.mirroring_state 
                                from msdb.sys.databases i
                                INNER JOIN msdb.sys.database_mirroring b
                                ON i.database_id = b.database_id
                                WHERE b.mirroring_state IS NOT NULL
                            '')'


        EXECUTE sys.sp_executesql @sql;
        FETCH NEXT FROM c1
    END
CLOSE c1
DEALLOCATE c1

Answer 1

OPENQUERY can only be used with a valid linked server reference. As per MSDN:

OPENQUERY ( linked_server ,'query' )

linked_server

Is an identifier representing the name of the linked server.

So you can't use servername\\instance as the first parameter. You'll have to create a linked server first, and then use the linked server name as the first parameter.

An example using dynamic SQL:

DECLARE @linked_server VARCHAR(20), @sql NVARCHAR(512);

SET @linked_server = 'SERVER1\INSTANCE1';
SET @sql = 'SELECT * FROM OPENQUERY([' + @linked_server + '], ''SELECT * FROM SomeTable;'');';

EXEC sys.sp_executesql @sql;