Oracle Service Name View
select name from V$SERVICES;
select name from V$ACTIVE_SERVICES;
Determined Dunlin
select name from V$SERVICES;
select name from V$ACTIVE_SERVICES;
SELECT VALUE FROM V$PARAMETER WHERE NAME = 'service_names';
SELECT NAME FROM V$SERVICES;
SELECT NAME FROM V$ACTIVE_SERVICES;
SELECT * FROM ALL_SERVICES;