Answers for "postgres list users"

mysql show users

select * from mysql.user;
#or for less data
select user, host from mysql.user;

postgresql list users

postgres=# \du

postgres list users

SELECT usename AS role_name,
       CASE
           WHEN usesuper AND usecreatedb THEN
               cast('superuser, create database' AS pg_catalog.text)
           WHEN usesuper THEN
               cast('superuser' AS pg_catalog.text)
           WHEN usecreatedb THEN
               cast('create database' AS pg_catalog.text)
           ELSE
               cast('' AS pg_catalog.text)
       END     AS role_attributes
FROM pg_catalog.pg_user
ORDER BY role_name DESC;

how to know the username of postgresql

SELECT current_user,
       user,
       session_user,
       current_database(),
       current_catalog,
       version();