create user and password postgres

ALTER USER davide WITH PASSWORD 'hu8jmn3';

sudo -u postgres psql postgres

# https://www.postgresql.org/docs/8.0/sql-createuser.html
CREATE USER <username> WITH PASSWORD '<password>' VALID UNTIL '<date here>';

sudo -u postgres psqlpostgres=# create database mydb;postgres=# create user myuser with encrypted password 'mypass';postgres=# grant all privileges on database mydb to myuser;

\password postgres

psql=# grant all privileges on database <dbname> to <username>

dropuser username