How to use ALTER USER command in PostgreSQL

ALTER USER changes the attributes of a PostgreSQL user account. 

Examples

1.Change a user's password:

  ALTER USER davide WITH PASSWORD 'hu8jmn3';

2.Change the expiration date of the user's password:

  ALTER USER manuel VALID UNTIL 'Jan 31 2030';

3.Change a password expiration date, specifying that the password        should expire at midday on 4th May 2005 using the time zone which is    one hour ahead of UTC:

  ALTER USER chris VALID UNTIL 'May 4 12:00:00 2005 +1';

4.Make a password valid forever:

  ALTER USER fred VALID UNTIL 'infinity';

5.Give a user the ability to create other users and new databases:

  ALTER USER miriam CREATEUSER CREATEDB;