FlyingZC opened a new issue, #27692:
URL: https://github.com/apache/shardingsphere/issues/27692

   # Background
   Hi community,
   
   ShardingSphere parser engine helps users parse a SQL to get the AST 
(Abstract Syntax Tree) and visit this tree to get SQLStatement (Java Object). 
Currently, we are planning to enhance the support for openGauss SQL parsing in 
ShardingSphere.
   
   More details:
   
https://shardingsphere.apache.org/document/current/en/reference/sharding/parse/
   
   # Task
   This issue is to support more openGauss sql parse, as follows:
   ```sql
    create function test_event_trigger() returns event_trigger as $$
   BEGIN
       RAISE NOTICE 'test_event_trigger: % %', tg_event, tg_tag;
   END
   $$ language plpgsql;
   
   --创建事件触发器函数(用于sql_drop事件)
   
   ```
   
   ```sql
    CREATE OR REPLACE FUNCTION drop_sql_command()
   RETURNS event_trigger AS $$
   BEGIN
   RAISE NOTICE '% - sql_drop', tg_tag;
   END;
   $$ LANGUAGE plpgsql;
   
   --创建事件触发器函数(用于table_rewrite事件)
   
   ```
   
   ```sql
    CREATE OR REPLACE FUNCTION test_evtrig_no_rewrite() RETURNS event_trigger
   LANGUAGE plpgsql AS $$
   BEGIN
     RAISE EXCEPTION 'rewrites not allowed';
   END;
   $$;
   
   --创建事件类型为ddl_command_start的事件触发器
   
   ```
   
   ```sql
    create event trigger regress_event_trigger on ddl_command_start
      execute procedure test_event_trigger();
   
   --创建事件类型为ddl_command_end的事件触发器
   
   ```
   
   ```sql
    create event trigger regress_event_trigger_end on ddl_command_end
      execute procedure test_event_trigger();
   
   --创建事件类型为sql_drop的事件触发器
   
   ```
   
   # Process
   1. First confirm that this is a correct openGauss sql syntax, if not please 
leave a message under the issue and ignore it;
   2. Compare SQL definitions in Official SQL Doc and ShardingSphere SQL Doc;
   3. If there is any difference in ShardingSphere SQL Doc, please correct them 
by referring to the Official SQL Doc;
   4. Run mvn install the current_file_module;
   5. Check whether there are any exceptions. If indeed, please fix them. 
(Especially xxxVisitor.class);
   6. Add new corresponding SQL case in SQL Cases and expected parsed result in 
Expected Statement XML;
   7. Run SQLParserParameterizedTest to make sure no exceptions.
   
   # Relevant Skills
   1. Master JAVA language
   2. Have a basic understanding of Antlr `g4` file
   3. Be familiar with openGauss SQLs


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