创建
create database link gadata0008
connect to gadata0008
identified by "gold"
using 'ORA11G';
删除数据库链接：drop database link linkname;
创建数据库链接：
create database link linkname
connect to username
identified by password
using 'connection string';
如果想建立全局链接，则需要使用关键字：public
create public
database link linkname
connect to username
identified by password
using 'connection string';
connection string可以有两种形式：
1，在文件tnsnames.ora配置的名称：
如：
CDRDL =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 10.147.129.29)(PORT = 2521))
)
(CONNECT_DATA =
(SERVICE_NAME = cdrdb)
)
)
此时可以写成：
create database link linkname
connect to username
identified by password
using 'CDRDL';
2，也可以直接使用‘=’号后面的字符串，
如：
create database link linkname
connect to username
identified by password
using '(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=10.147.129.29)(PORT=2521)))(CONNECT_DATA=(SERVICE_NAME=cdrdb)))';
查询使用：
select * from
item@gadata0008.regress.rdbms.dev.us.oracle.com
create or replace synonym ERP2_ORG_DUMMY_LOG
for ORG_DUMMY_LOG@ERP2.REGRESS.RDBMS.DEV.US.ORACLE.COM;