CREATE USER --+---> <username> ----> IDENTIFIED EXTERNALLY --+-----+
                +---> PUBLIC ----------------------------------+     |
  +------------------------------------------------------------------+
  +-------------+-------------------------------+-------------------->
                +---> create-user-opts ---------+

  create-user-opts =

  -+-> ACCOUNT --+->LOCK ---+---------------------+-->
   |             +->UNLOCK -+                     |
   +-> COMMENT IS -+-> '<string>' --+-------------+
   |               +------- / <-----+             |
   +-> NO PROFILE  -------------------------------+
   +-> PROFILE <profile_name> --------------------+