text: --  @testpoint:opengauss关键字Implicit(非保留)，自定义数据类型名为explain
  --关键字explain作为数据类型不带引号，创建成功
  drop type if exists Implicit;
  CREATE TYPE Implicit AS (f1 int, f2 text);
  select typname from pg_type where typname ='Implicit';
  drop type Implicit;
  
  
  --关键字explain作为数据类型加双引号，创建成功
  drop type if exists "Implicit";
  CREATE TYPE "Implicit" AS (f1 int, f2 text);
  select typname from pg_type where typname ='Implicit';
  drop type "Implicit";
  
  --关键字explain作为数据类型加单引号，合理报错
  drop type if exists 'Implicit';
  CREATE TYPE 'Implicit' AS (f1 int, f2 text);
  select * from pg_type where typname ='Implicit';
  drop type 'Implicit';
  
  --关键字explain作为数据类型加反引号，合理报错
  drop type if exists `Implicit`;
  CREATE TYPE `Implicit` AS (f1 int, f2 text);
  select * from pg_type where typname =`Implicit`;
  drop type `Implicit`;