How to get Service Name through Oracle Oracle Developer

To see what services are available in the database use following queries:
select name from V$SERVICES;
select name from V$ACTIVE_SERVICES;

The V$ views are mainly dynamic views of system metrics. They are used for performance tuning, session monitoring, etc. So access is limited to DBA users by default

The easiest way of finding the database name is:
select * from global_name;

This view is granted to PUBLIC, so anybody can query it.