Lista todos os usuários em um banco de dados postgres.
SELECT u.usename AS "User name",
u.usesysid AS "User ID",
CASE WHEN u.usesuper AND u.usecreatedb THEN CAST('superuser, create
database' AS pg_catalog.text)
WHEN u.usesuper THEN CAST('superuser' AS pg_catalog.text)
WHEN u.usecreatedb THEN CAST('create database' AS
pg_catalog.text)
ELSE CAST('' AS pg_catalog.text)
END AS "Attributes"
FROM pg_catalog.pg_user u
ORDER BY 1;