oracle 查询所有表的列信息

select a.column_name 列名,a.comments 注释, a.OWNER 用户名, a.TABLE_NAME 表名
  from sys.all_col_comments a,
       sys.dba_objects b
 where a.table_name=b.object_name 
   and b.object_type='TABLE'
 order by a.COLUMN_NAME;