ORACLE中怎样建DBLINK到异构数据库？

请参考.

--建立ORACLE到SQL SERVER的分布式--
1、安装 Microsoft Data Access Components (MDAC)SDK ODBC driver

2、test whether CATHS has run.connect to the Oracle server
as schema "SYSTEM" and do "DESCRIBE SYS.HS_FDS_CLASS".
If it does not exist, connect as SYS (or internal) and run
the CATHS script. (ORACLE_HOME\RDBMS\ADMIN\CATHS.SQL)

3、建立 SQL SERVER 数据源
TEST_SQLSERVER

4、配置tnsnames.ora. (ORACLE_HOME\NETWORK\ADMIN)
TEST_SQLSERVER =
(DESCRIPTION=
(ADDRESS=
(PROTOCOL=tcp)
(HOST=

 1<ip地址>)   
 2(PORT=1521)   
 3)   
 4(CONNECT_DATA=   
 5(SID=TEST_SQLSERVER)   
 6)   
 7(HS=)   
 8)   
 9  
105、配置listener.ora. (ORACLE_HOME\NETWORK\ADMIN)   
11(SID_DESC=   
12(SID_NAME=TEST_SQLSERVER)   
13(ORACLE_HOME=D:\Oracle\iSuites)   
14(PROGRAM=hsodbc)   
15)   
16  
176、重启ORACLE监听.   
18CMD   
19LSNRCTL STOP   
20LSNRCTL START   
21LSNRCTL STATUS   
22  
237、添加网关配置文件. (ORACLE_HOME\HS\ADMIN)   
24文件名为:initTEST_SQLSERVER.ora   
25文件内容:   
26#   
27# HS init parameters   
28#   
29HS_FDS_CONNECT_INFO = TEST_SQLSERVER   
30HS_FDS_TRACE_LEVEL = 0   
31#HS_FDS_TRACE_FILE_NAME = TEST_SQLSERVER.trc   
32  
33#   
34# Environment variables required for the non-Oracle system   
35#   
36#set <envvar>=<value>   
37  
388、进入ORACLE SQL*PLUS,建立数据库链.   
39CREATE DATABASE LINK TOSQL USING 'TEST_SQLSERVER';</value></envvar></ip地址>