Describe how Linked server is used to excess external data.
A linked server can be considered as another SQL server database running elsewhere. It can be a OLEDB or ODBC data source. They help in addressing distributed queries.
OPENQUERY function is used for such purposes. This function I is used to execute the specified query on the linked sever. OPENQUERY can be referenced in from the FROM clause just like a table name.
Example:SELECT * FROM OPENQUERY(OracleSvr, 'SELECT name, id FROM joe.titles')
