Unload data and turn into external table using Oracle10g datapump

-- create DIRECTORY

CREATE OR REPLACE DIRECTORY ETL_EXT_TABS AS 'C:\ext_tab\';
GRANT READ ON DIRECTORY ETL_EXT_TABS TO orion;
GRANT WRITE ON DIRECTORY ETL_EXT_TABS TO orion;

-- unload Table DEPT and turn into an external table TMP_EXT_TABLE1

create table TMP_EXT_TABLE1
organization external
(type oracle_datapump
default directory ETL_EXT_TABS
location('XX.TXT'))
as select * from DEPT;

-- unload table D_N_USER of Heterogeneous database(SQL2000)
-- and turn into an external table TMP_EXT_USER

create table TMP_EXT_USER
organization external
(type oracle_datapump
default directory ETL_EXT_TABS
location('D_N_USER.TXT'))
as select * from D_N_USER@SQLSVR;