使Oracle能同时访问多个SQL Server

如何在Oracle里设置访问多个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。

1、在安装了Oracle9i Standard Edition或者Oracle9i Enterprise Edition的windows机器上(IP:192.168.0.2), 产品要选了透明网关(Oracle Transparent Gateway)里访问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_HOSTNMAE;DATABASE=pubs"HS_DB_NAME=pubsHS_FDS_TRACE_LEVEL=OFFHS_FDS_RECOVERY_ACCOUNT=RECOVERHS_FDS_RECOVERY_PWD=RECOVERinitnorthwind.ora内容如下:HS_FDS_CONNECT_INFO="SERVER=sqlserver_hostname;DATABASE=Northwind"HS_DB_NAME=NorthwindHS_FDS_TRACE_LEVEL=OFFHS_FDS_RECOVERY_ACCOUNT=RECOVERHS_FDS_RECOVERY_PWD=RECOVER$ORACLE9I_HOME\network\admin 下listener.ora内容如下:LISTENER = (DESCRIPTION_LIST = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.0.2)(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:192.168.0.2)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陆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;...... ......

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-----980569278996745980149001989076

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) )

需要sqlserver_databaseid一致才行。