1、创建数据库连接：

--授权
grant create public database link to XXX;
grant create database link to XXX;

--删除权限（更改的时候需要用到）
grant drop public database link to XXX;
grant drop database link to XXX;

--创建database link

create database link database_link_name
connect to username identified by "password"
using '(DESCRIPTION =
	(ADDRESS_LIST =
	(ADDRESS = (PROTOCOL = TCP)(HOST = IP)(PORT = 1521))
	)
	(CONNECT_DATA =
			(SERVICE_NAME = orcl)
	)
	)';