"Post-it" for create user + database and assign database to user in PostgreSQL.

Create user + database -> assign database to user in PostgreSQL

- terminal:
  createuser -P user_name

- Answer questions:
  enter password for new role: 
  Enter it again: 
  Shall the new role be a superuser? (y/n) n
  Shall the new role be allowed to create databases? (y/n) n
  Shall the new role be allowed to create more new roles? (y/n) n

- terminal:
  createdb db_name
  
- terminal:
  psql db_name
  grant all privileges on database db_name to user_name;