hi, can you list me the user name and the password of the most popular role user?
select user_name, password from users group by role_code order by count ( * ) desc limit 1
great, how many popular role users are?
select count ( * ) from users group by role_code order by count ( * ) desc limit 1
Can you list me all the username of users with the most popular role?
select user_name from users group by role_code order by count ( * ) desc limit 1
Ok,  show me the username of an unpopular user.
select user_name from users where user_name not in ( select user_name from users group by role_code order by count ( * ) desc limit 1 )