請問oracle 怎么生成腳本？

用下面的脚本可以生成某个用户下的表的DDL语句： 

set arraysize 1 

set echo off 

set heading off 

set feedback off 

set verify off 

set pagesize 0 

set linesize 79 

define 1 = &&SCHEMA_NAME 

spool tbl_&&SCHEMA_NAME 

set termout off 

col x noprint 

col y noprint 

select  'rem   ****    Create Table DDL for '||chr(10)|| 

        'rem   ****    '||username||''''||'s tables'||chr(10)||chr(10) 

from    dba_users 

where     username      = upper ('&&1') 

/ 

select  table_name y, 

        0 x, 

        'create table ' || 

        rtrim(table_name) || 

        '(' 

from    dba_tables 

where     owner = upper('&&1') 

union 

select  tc.table_name y, 

        column_id x, 

        rtrim(decode(column_id,1,null,','))|| 

        rtrim(column_name)|| ' ' || 

        rtrim(data_type) || 

        rtrim(decode(data_type,'DATE',null,'LONG',null, 

               'NUMBER',decode(to_char(data_precision),null,null,'('), 

               '(')) || 

        rtrim(decode(data_type, 

               'DATE',null, 

               'CHAR',data_length, 

               'VARCHAR2',data_length, 

               'NUMBER',decode(to_char(data_precision),null,null, 

                 to_char(data_precision) || ',' || to_char(data_scale)), 

               'LONG',null, 

               '******ERROR')) || 

        rtrim(decode(data_type,'DATE',null,'LONG',null, 

               'NUMBER',decode(to_char(data_precision),null,null,')'), 

               ')')) || ' ' || 

        rtrim(decode(nullable,'N','NOT NULL',null)) 

from    dba_tab_columns tc, 

        dba_objects o 

where   o.owner = tc.owner 

and     o.object_name = tc.table_name 

and     o.object_type = 'TABLE' 

and     o.owner = upper('&&1') 

union 

select  table_name y, 

        999999 x, 

        ')'  || chr(10) 

        ||' STORAGE('                           || chr(10) 

        ||' INITIAL '    || initial_extent      || chr(10) 

        ||' NEXT '       || next_extent         || chr(10) 

        ||' MINEXTENTS ' || min_extents         || chr(10) 

        ||' MAXEXTENTS ' || max_extents         || chr(10) 

        ||' PCTINCREASE '|| pct_increase        || ')' ||chr(10) 

        ||' INITRANS '   || ini_trans         || chr(10) 

        ||' MAXTRANS '   || max_trans         || chr(10) 

        ||' PCTFREE '    || pct_free          || chr(10) 

        ||' PCTUSED '    || pct_used          || chr(10) 

        ||' PARALLEL (DEGREE ' || DEGREE || ') ' || chr(10) 

        ||' TABLESPACE ' || rtrim(tablespace_name) ||chr(10) 

        ||'/'||chr(10)||chr(10) 

from    dba_tables 

where   owner = upper('&&1') 

order by 1,2 

/

select dbms_metadata.getddl('TABLE','表名') from dual;  --一个表

select dbms_metadata.getddl('TABLE',table_name) from user_tables; --用户所有表