User and Schema both are interchangable words. A user is attached to only one schema.
Schema is nothing but collection of database objects like tables, materialised views, synonyms, views, indexes, sequences, packages, procedures, functions, triggers etc....
Note : delete + commit is going to delete all the records permanently without releasing the extents to the datafile.
Truncate is going to delete all the records permanently but releases all the extents to the datafile just by retaining the initial extent.
User management is one of the important aspect for a DBA.
DBA has to safe guard the objects created by the developers otherwise it leads to security concern.
The moment once we create a database, default users that are created are
1.sys(super user)
2.system
3.dbsnmp(required for oracle networking)
4.outln(contains stored outlines)
5.sysman(required for oracle enterprise manager console)
Once we create a database recommanded to change the default passwords of all the default users.
Users contain some privileges. Privilege is a right to execute a specific task or specific statement.
