A linked server allows the SQL Server Database Engine to execute commands against OLE DB data sources.
Linked servers are configured to enable the Database Engine to execute a Transact-SQL statement to another instance of SQL Server or another database such as Oracle.
OLE DB data sources can be configured as linked servers like Microsoft Access and Excel.
Advantages:
- access data from outside of SQL Server.
- execute distributed commands( queries updates, transaction) to heterogeneous data sources
Examples:
Add Microsoft Access as linked server
