text: --  @testpoint:opengauss关键字nullif(非保留)，作为用户组名
  
  
  --关键字不带引号-成功
  drop group if exists nullif;
  create group nullif with password 'gauss@123';
  drop group nullif;
  
  --关键字带双引号-成功
  drop group if exists "nullif";
  create group "nullif" with password 'gauss@123';
  drop group "nullif";
  
  --关键字带单引号-合理报错
  drop group if exists 'nullif';
  create group 'nullif' with password 'gauss@123';
  
  --关键字带反引号-合理报错
  drop group if exists `nullif`;
  create group `nullif` with password 'gauss@123';
  