sqlplus / as sysdba
ALTER SESSION SET "_ORACLE_SCRIPT"=true;     -- Warning !
-- c## prefixe
CREATE USER c##username IDENTIFIED BY "my_password";
GRANT CONNECT TO MY_USER;           -- To connect to DB
GRANT RESOURCE TO MY_USER;          -- Access / modify
GRANT MY_ROLE TO MY_USER;           -- Grants a role (to be defined)
GRANT CREATE SESSION TO MY_USER;