Oracle查询简单数据字典SQL语句

SELECT TAB.*,COL.DATA_TYPE,COL.DATA_LENGTH

  FROM (SELECT TAB_COM.TABLE_NAME,

               TAB_COM.COMMENTS TAB_COMM,

               COL_COM.COLUMN_NAME,

               COL_COM.COMMENTS COL_COMM

          FROM USER_TAB_COMMENTS TAB_COM

          LEFT JOIN USER_COL_COMMENTS COL_COM ON TAB_COM.TABLE_NAME =

                                                 COL_COM.TABLE_NAME

         WHERE TAB_COM.TABLE_TYPE = 'TABLE') TAB

  LEFT JOIN USER_TAB_COLUMNS COL ON TAB.TABLE_NAME = COL.TABLE_NAME

                                AND TAB.COLUMN_NAME = COL.COLUMN_NAME