create or replace FUNCTION helpdesk_auth (
    p_username IN VARCHAR2,
    p_password IN VARCHAR2)
RETURN BOOLEAN IS
BEGIN
  FOR c1 IN (SELECT 1 
              FROM helpdesk_user
             WHERE upper(user_login) = upper(p_username)
               AND upper(user_password) = upper(p_password))
  LOOP
    RETURN TRUE;
  END LOOP;
  RETURN FALSE;
END;​