多数据库访问:(sysdba mode)
 create public database link logs  connect to gmnr identified by pass using '(DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.243.26)(PORT = 1521))) (CONNECT_DATA = (SERVICE_NAME = gmnr.bbb.aaa.com)))';
    create public database link logs1  connect to logstore identified by pass using 'aaab'; (未成功)
 select * from tableOnDB2@db2; (SYNONYM同义词可以被创建以代用)。 (normal & sysdba mode)
 删除dblink:DROP  PUBLIC  DATABASE  LINK logs1;
 
多用户访问:
    select * from user2.tableOfUser2(SYNONYM同义词可以被创建以代用);