Describes the type of connection in use for the connection, including the server host name.
link_identifier
The MySQL connection. If the link identifier is not specified, the last link opened by mysql_connect() is assumed. If no such link is found, it will try to create one as if mysql_connect() was called with no arguments. If by chance no connection is found or established, an E_WARNING level warning is generated.
Returns a string describing the type of MySQL connection in use for the connection or FALSE on failure.