ORACLE实现异种数据库连接服务的技术叫做透明网关（Transparent Gateway）。
目前ORACLE利用透明网关可以实现和SQL SERVER、SYBASE、DB2等多种主流数据库的互联。
现在通过oracle访问sybase数据库，把配置oracle9i TRANSPARENT GATEWAY FOR SYBASE的步骤写成文档，供需要的网友参考！
配置TRANSPARENT GATEWAY FOR SYBASE步骤
1.oracle所在服务器上安装sybase client（或者在同一台server上安装oracle、sybase服务器）确保能够访问sybase数据库
2.安装TRANSPARENT GATEWAY FOR SYBASE选件，要用自定义安装。
正确选择sybase的安装目录
3.选择一个sid字符串准备赋给sybase数据库。
如：tg4sybs设置SYBASE的dll路径到环境变量PATH（这一步很重要）
4.修改初始化文件，默认的是：
ORACLE_HOME\tg4sybs\admin\inittg4sybs.ora
设置参数
HS_FDS_CONNECT_INFO
格式：HS_FDS_CONNECT_INFO= server_name. database_name[,INTERFACE= interface_file]
server_name. database_name是大小写敏感的。
INTERFACE可选
例子：如下
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
# This is a sample agent init file that contains the HS parameters that are
# needed for the Transparent Gateway for Sybase
#
# HS init parameters
#
HS_FDS_CONNECT_INFO=migration_serv.tax
HS_FDS_TRACE_LEVEL=OFF
HS_FDS_RECOVERY_ACCOUNT=RECOVER
HS_FDS_RECOVERY_PWD=RECOVER
#
# Environment variables required for Sybase
#
set SYBASE=d:\sybase
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
上例中
server_name是migration_serv
database_name是tax
5.配置oracle网络服务的listener,配置文件是：listener.ora
默认路径：ORACLE_HOME\network\admin
加入如下
SID_LIST_LISTENER=
(SID_LIST=
(SID_DESC=
(SID_NAME= gateway_sid)
(ORACLE_HOME= oracle_home_directory)
(PROGRAM=tg4sybs)
)
)
gateway_sid就是3选择的sid字符串
oracle_home_directory是ORACLE_HOME
tg4sybs若是SYBASE是特定的。如果是其他数据库，会不同。
例子如下：
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
(SID_DESC=
(SID_NAME=tg4sybs)
(ORACLE_HOME = D:\oracle\ora92)
(PROGRAM=tg4sybs)
)
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
6.停止监听
lsnrctl stop
重新启动监听程序
lsnrctl start
7.配置oracle server的tnsnames.ora使其能够访问sybase
connect_descriptor=
(DESCRIPTION=
(ADDRESS=
(PROTOCOL=TCP)
(HOST= host_name)
(PORT= port_number)
)
(CONNECT_DATA=
(SID= gateway_sid))
(HS=OK))
connect_descriptor是连接串，任取，一般为sybs
host_name：oracle server的name
port_number：oracle监听端口
gateway_sid就是3选择的sid字符串
例子如下：
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
sybs=
(DESCRIPTION=
(ADDRESS_LIST =
(ADDRESS=(PROTOCOL=TCP)(HOST= dw-server1)(PORT= 1521))
)
(CONNECT_DATA=
(SID= tg4sybs)
)
(HS=OK)
)
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
8.建立database link
如：
CREATE DATABASE LINK sybs CONNECT TO sa
IDENTIFIED BY prient
USING 'SBYS' ；
即可访问sybase 数据库。
需要注意的是，sybase数据库的表名，字段名，如果是小写的，那么在oracle里访问的时候要加上双引号""
如：
SQL〉select "a" from "b"@sybs;
