For an instructor lead, in-depth look at learning SQL click below.
Working with linked servers in SQL Server provides a seamless way to access and manipulate data across multiple servers. In essence, a linked server allows SQL Server to execute commands against databases on a remote server. In this blog post, we will discuss SQL Server linked servers and how to utilize SQL code to work with them effectively.
Creating a Linked Server
To create a linked server, the sp_addlinkedserver stored procedure can be used in SQL Server. Below is a basic example of how to use this procedure:
|
1 2 3 4 5 6 7 8 |
EXEC s<a href="mailto:p_addlinkedserver @server='LINKEDSERVER1'" >p_addlinkedserver @server='LINKEDSERVER1'</a>, @srvproduct='', @provider='SQLNCLI', @datasrc='SERVERNAME' |
In the above code, we are adding a linked server named ‘LINKEDSERVER1’. ‘SQLNCLI’ represents the SQL Server Native Client, which is the provider, and ‘SERVERNAME’ is the name of the remote server.
Querying a Linked Server
Once the linked server is set up, querying it is straightforward. The linked server’s name is used in the FROM clause, as shown below:
|
1 2 3 4 |
SELECT * FROM LINKEDSERVER1.database.dbo.table |
In the above query, we’re asking for all records (*) from a table located on the ‘LINKEDSERVER1’ server’s database.
Updating a Linked Server
Updating data in a linked server can be achieved similar to a local server. However, you must use a four-part name in the UPDATE statement for the target table as shown below:
|
1 2 3 4 5 |
UPDATE LINKEDSERVER1.database.dbo.table SET column = 'newValue' WHERE column = 'oldValue' |
Deleting a Linked Server
To remove a linked server, we can utilize the sp_dropserver stored procedure like so:
|
1 2 3 |
EXEC sp_dropserver 'LINKEDSERVER1', 'droplogins' |
In the above code, the first attribute is the linked server’s name, and the ‘droplogins’ option instructs SQL Server to also remove any associated logins with the linked server.
Conclusion
In this blog post, we explored the concept of Linked Servers in SQL Server and relevant SQL codes to create, access, modify, and delete linked servers. These elements add to the versatility of SQL Server, allowing seamless data querying and manipulation across multiple servers.
Note:Always ensure that you have the necessary permissions when working with linked servers, and be mindful of the impact your queries might have on the performance of the remote server.