Auth. funkcija

create or replace function my_app_auth (
  p_username in varchar2
 ,p_password in varchar2
) return boolean is
  v_ret   boolean := false;
  v_count pls_integer := 0;
begin
  if p_username is not null and p_password is not null then
    select count(*)
      into v_count
      from app_users
     where username = p_username
       and password = p_password;
  end if;

  v_ret := v_count > 0;

  return v_ret;

exception
  when others then
    -- log error...
    return false;
end my_app_auth;