function my_auth (p_username in varchar2, p_password in varchar2)
return boolean as found number := 0;
begin
select 1 into found from my_users where upper(user_name) = upper(p_username)
and upper(user_password) = upper(p_password) and user_activated = 1;
return true;
exception
when NO_DATA_FOUND then return false;
end;