bif_set_user_id (caddr_t * qst, caddr_t * err_ret, state_slot_t ** args)
{
  query_instance_t *qi = (query_instance_t *) QST_INSTANCE (qst);
  client_connection_t * cli = qi->qi_client;
  caddr_t uname = bif_string_arg (qst, args, 0, "__set_user_id");
  long mode = BOX_ELEMENTS (args) > 1 ? (long) bif_long_arg (qst, args, 1, "__set_user_id") : 1;
  caddr_t pass = BOX_ELEMENTS (args) > 2 ? bif_string_arg (qst, args, 2, "__set_user_id") : NULL;
  user_t * user = sec_name_to_user (uname);

  if (!user /*|| !user->usr_is_sql*/ || user->usr_is_role)
    sqlr_new_error ("22023", "HT042", "Not valid user id \"%s\"", uname);

  if (pass && (0 != strcmp (pass, user->usr_pass) || user->usr_disabled))
    sqlr_new_error ("22023", "HT042", "Invalid credentials for user id \"%s\"", uname);

  if (!pass)
    sec_check_dba ((query_instance_t *) qst, "__set_user_id");

  set_user_id (cli, uname, NULL);
  qi->qi_pop_user = mode;
  qi->qi_u_id = user->usr_id;
  qi->qi_g_id = user->usr_g_id;

  return (box_num (0));
}