SQL Server: Link two Databases from two different SQL Servers

How to link Two SQL Servers

Execute the following system Stored Procedure to create new SQL Server that you want to link to: 

sp_addlinkedserver 'TestServer1','','SQLNCLI','192.199.121.12\SQLEXPRESS',null,NULL,NULL 

Now, by executing the first command, your linked server is created. But still you need to create the user to login to that linked server. To do this, execute the following system Stored Proc: 

exec sp_addlinkedsrvlogin ' TestServer1','false',null,'username','password' 

 Now, try to run the any query of the database connected to that linked server

E.g: Select * From TestServer1.DatabaseName.[dbo].tableName