In this bog, I will explain you how the user management work in oracle 12c. Starting from Oracle 12C there are two types of user. - Common User - Local User Common User - Common user have the access to all PDB except seed pdb - Common user start with C## prefix - SYS and SYSTEM are the common user created by oracle - If specifying the DEFAULT TABLESPACE, TEMPORARY TABLESPACE, QUOTA and PROFILE clauses as part of CREATE USER ,then you must ensure that those objects existing in all containers (PDB) below the CDB - User-created schema objects owned by COMMON USERS cannot be shared across PDB boundaries - Common user will be visible in container as well as pluggable database - It is not recommended to create objects under common user Local User

- Local user will be created under PDB database only - Local user will be visible to respective pdb and hide from another pdb - Don’t need prefix as C## for creating local user