text: --  @testpoint:opengauss关键字cross(保留)，作为函数名
  
  --关键字不带引号-成功
  create function cross(i integer)
  returns integer
  as $$
  begin
      return i+1;
  end;
  $$ language plpgsql;
  /
  
  --清理环境
  drop function cross(i integer);
  
  --关键字带双引号-成功
  create function "cross"(i integer)
  returns integer
  as $$
  begin
      return i+1;
  end;
  $$ language plpgsql;
  /
  
  --清理环境
  drop function "cross"(i integer);
  
  --关键字带单引号-合理报错
  create function 'cross'(i integer)
  returns integer
  as $$
  begin
      return i+1;
  end;
  $$ language plpgsql;
  /
  
  --关键字带反引号-合理报错
  drop function if exists `cross`;
  create function `cross`(i integer)
  returns integer
  as $$
  begin
      return i+1;
  end;
  $$ language plpgsql;
  /