ماهو الفرق بين SID وال global database name في أوراكل

ولماذا دائما نفس الإسم

Sid= SID(system identifier) is a unique name for an Oracle database instance.

DB Name(database name) = Name of the database (database can be shared between multiple instances )

Instance Name = it is same as Oracle SID.

service name =SERVICE NAMES specifies one or more names for the database service to which this instance connects.

Listener : The Listener is a named process which runs on the Oracle Server, awaiting requests from Clients to connect to the Instance