如果创建,删除或重命名base1中的列,我想用ddl触发器重新创建视图view1.

create event trigger base1_views
   on ddl_command_end
   when tag in( 'ALTER TABLE' )
   execute procedure base1_views_fn();

create function base1_views_fn() returns void as $$
declare
  buf varchar;
begin
  -- is table being altered = 'base'?
  -- add,drop or renaming a column?
  buf = 'drop view view1';
  execute buf;
  buf = 'create view view1 as select * from base1 where ...';
  execute buf;
end;
$$language 'plpgsql';

在函数base1_views_fn()中,我们如何获取表名以及是否要更改列？