Oracle SQL Query for listing all Schemas in a DB

Question

I wanted to delete some unused schemas on our oracle DB.

How can I query for all schema names ?

Answer 1

Below sql lists all the schema in oracle that are created after installation ORACLE_MAINTAINED='N' is the filter. This column is new in 12c.

select distinct username,ORACLE_MAINTAINED from dba_users where ORACLE_MAINTAINED='N';