有没有办法用一个命令生成所有ddl？ (或者一些命令？)

编辑：
根据下面的建议,我试过：

SELECT dbms_Metadata.get_ddl( 'TABLE',table_name,owner )
  FROM all_tables;

得到了：

ORA-31603: object "HS_PARTITION_COL_NAME" of type TABLE not found in schema "SYS"
ORA-06512: at "SYS.DBMS_SYS_ERROR",line 105
ORA-06512: at "SYS.DBMS_MetaDATA",line 3241
ORA-06512: at "SYS.DBMS_MetaDATA",line 4812
ORA-06512: at line 1
31603. 00000 -  "object \"%s\" of type %s not found in schema \"%s\""
*Cause:    The specified object was not found in the database.
*Action:   Correct the object specification and try the call again.

很明显,我不了解dbms_Metadata有一些非常基本的东西.