在ORACLE里通过异构服务设置访问多个SQL Server数据库

假设我们要在ORACLE里同时能访问SQL Server里默认的pubs和Northwind两个数据库。

可参考最初写的通过异构服务链接oracle 和sql server 数据库服务器

1、在安装了ORACLE9i Standard Edition或者ORACLE9i Enterprise Edition的windows机器上(IP:192.168.0.1),
产品要选了透明网关(Oracle Transparent Gateway)里要访问Microsoft SQL Server数据库.

$ORACLE9I_HOME/tg4msql/admin下新写initpubs.ora和initnorthwind.ora配置文件
initpubs.ora内容如下:
HS_FDS_CONNECT_INFO="SERVER=sqlserver_hostname;DATABASE=pubs"
HS_DB_NAME=pubs
HS_FDS_TRACE_LEVEL=OFF
HS_FDS_RECOVERY_ACCOUNT=RECOVER
HS_FDS_RECOVERY_PWD=RECOVER

initnorthwind.ora内容如下:
HS_FDS_CONNECT_INFO="SERVER=sqlserver_hostname;DATABASE=Northwind"
HS_DB_NAME=Northwind
HS_FDS_TRACE_LEVEL=OFF
HS_FDS_RECOVERY_ACCOUNT=RECOVER
HS_FDS_RECOVERY_PWD=RECOVER

(蓝色字的部分可以根据具体要访问的SQL Server数据库的情况而修改)

$ORACLE9I_HOME/network/admin 下listener.ora内容如下:

LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.0.1)(PORT = 1521))
)
)
)

SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(GLOBAL_DBNAME = test9)
(ORACLE_HOME = d:/oracle/ora92)
(SID_NAME = test9)
)
(SID_DESC=
(SID_NAME=pubs)
(ORACLE_HOME=d:/Oracle/Ora92)
(PROGRAM=tg4msql)
)
(SID_DESC=
(SID_NAME=northwind)
(ORACLE_HOME=d:/Oracle/Ora92)
(PROGRAM=tg4msql)
)
)

重启动这台做gateway的windows机器上(IP:192.168.0.1)TNSListener服务.

(凡是按此步骤新增可访问的SQL Server数据库时，TNSListener服务都要重启动)

2、ORACLE8I，ORACLE9I的服务器端配置tnsnames.ora, 添加下面的内容:

pubs =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.0.2)(PORT = 1521))
)
(CONNECT_DATA =
(SID = pubs)
)
(HS = pubs)
)

northwind =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.0.2)(PORT = 1521))
)
(CONNECT_DATA =
(SID = northwind)
)
(HS = northwind)
)

保存tnsnames.ora后,在命令行下

tnsping pubs
tnsping northwind

出现类似提示，即为成功
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.0.2)
(PORT = 1521))) (CONNECT_DATA = (SID = pubs)) (HS = pubs))
OK（20毫秒）

Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.0.2)
(PORT = 1521))) (CONNECT_DATA = (SID = northwind)) (HS = northwind))
OK（20毫秒）

设置数据库参数global_names=false。

设置global_names=false不要求建立的数据库链接和目的数据库的全局名称一致。
global_names=true则要求, 多少有些不方便。

oracle9i和oracle8i都可以在DBA用户下用SQL命令改变global_names参数

alter system set global_names=false;

建立公有的数据库链接:

create public database link pubs connect to testuser identified by testuser_pwd using 'pubs';

create public database link northwind connect to testuser identified by testuser_pwd using 'northwind';

(假设SQL Server下pubs和northwind已有足够权限的用户登录testuser,密码为testuser_pwd)

访问SQL Server下数据库里的数据:

select * from stores@pubs;
...... ......

select * from region@northwind;
...... ......

使用sql *plus copy命令从本地数据库复制暑假到MS SQL SERVER中：

copy from scott/tiger@myoracle insert EMP@pubs using select * from EMP

3、使用时的注意事项

ORACLE通过访问SQL Server的数据库链接时，用select * 的时候字段名是用双引号引起来的。

例如：
create table stores as select * from stores@pubs;

select zip from stores；

ERROR 位于第 1 行:
ORA-00904: 无效列名

select "zip" from stores;

zip
-----
98056
92789
96745
98014
90019
89076

已选择6行。

用SQL Navigator或Toad看从SQL Server转移到ORACLE里的表的建表语句为:

CREATE TABLE stores
("stor_id" CHAR(4) NOT NULL,
"stor_name" VARCHAR2(40),
"stor_address" VARCHAR2(40),
"city" VARCHAR2(20),
"state" CHAR(2),
"zip" CHAR(5))
PCTFREE 10
PCTUSED 40
INITRANS 1
MAXTRANS 255
TABLESPACE users
STORAGE (
INITIAL 131072
NEXT 131072
PCTINCREASE 0
MINEXTENTS 1
MAXEXTENTS 2147483645
)
/

总结: WINDOWS下ORACLE9i网关服务器在$ORACLE9I_HOME/tg4msql/admin目录下的initsqlserver_databaseid.ora

WINDOWS下ORACLE9i网关服务器listener.ora里面
(SID_DESC=
(SID_NAME=sqlserver_databaseid)
(ORACLE_HOME=d:/Oracle/Ora92)
(PROGRAM=tg4msql)
)

UNIX或WINDOWS下ORACLE8I,ORACLE9I服务器tnsnames.ora里面
northwind =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.0.2)(PORT = 1521))
)
(CONNECT_DATA =
(SID = sqlserver_databaseid)
)
(HS = sqlserver_databaseid)
)

sqlserver_databaseid一致才行.