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.

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