This will happen if the administrator has not created a PostgreSQL user account for you. (PostgreSQL user accounts are distinct from operating system user accounts.) If you are the administrator, see 第二十章 for help creating accounts. You will need to become the operating system user under which PostgreSQL was installed (usually postgres) to create the first user account. It could also be that you were assigned a PostgreSQL user name that is different from your operating system user name; in that case you need to use the -U switch or set the PGUSER environment variable to specify your PostgreSQL user name
postgres=# ALTER USER new_username SUPERUSER CREATEDB;
ALTER ROLE
为了确认一切顺利,
postgres=# \du
List of roles
Role name | Attributes | Member of
-----------+------------------------------------------------+-----------
new_username | Superuser, Create DB | {}
postgres | Superuser, Create role, Create DB, Replication | {}
root | Superuser, Create role, Create DB | {}
postgres=#