CREATE OR REPLACE PROCEDURE     get_next_session_id
(v_session_id OUT VARCHAR2)

IS
  BEGIN
  SELECT
         'S'||lpad(session_id.nextval,5,'0')
     INTO
         v_session_id
     FROM dual;
  EXCEPTION
     WHEN NO_DATA_FOUND
          THEN raise_application_error(-20000, 'No more rows.');
     WHEN OTHERS
          THEN raise_application_error(-20001, 'There was an undeterminable error.');
END get_next_session_id;