Users initiate a connect request by passing a user name and password, along with a net service name in a connect string, for the service to which they want to connect:
For instance with SqlPlus - SqlPlus Command :
Depending on your needs, net service names can be stored in a variety of places, including:
- Local configuration file, tnsnames.ora, on each client
- Directory server
- External naming service, such as NIS
It is used to define the database service where you want to make a connection.
net_service_name = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED ) (SID = orcl)))