Find out the user and its privileges in Oracle
Check all user having administrative privileges
Check all system privileges granted related to all users/roles.
GRANTEE is the name, role, or user that was assigned the privilege.
PRIVILEGE is the privilege that is assigned.
ADMIN_OPTION indicates if the granted privilege also includes the ADMIN option.
Check object level privileges to User
GRANTEE is the name of the user with granted access.
TABLE_NAME is the name of the object (table, index, sequence, etc).
PRIVILEGE is the privilege assigned to the GRANTEE for the associated object.
Check all the roles granted to users/roles
Check all the column level privileges for user/role
Find out current user permissions
select * from USER_ROLE_PRIVS where USERNAME = USER;
select * from USER_TAB_PRIVS where GRANTEE = USER;
select * from USER_SYS_PRIVS where USERNAME = USER;