--创建dblink

    CREATE PUBLIC DATABASE LINK weixinDDL CONNECT TO WEIXIN_FJ IDENTIFIED BY weixin_fj USING 'WEIXIN_FJ';

    CREATE SHARED PUBLIC  DATABASE LINK weixinDDL2 AUTHENTICATED BY WEIXIN_FJ IDENTIFIED BY weixin_fj USING 'WEIXIN_FJ';

    --*  

    create  database link weixinDDL4 connect to WEIXIN_FJ identified by WEIXIN_FJ 

    using '(DESCRIPTION =

      (ADDRESS_LIST =

        (ADDRESS = (PROTOCOL = TCP)(HOST = 221.130.48.67)(PORT = 1521))

      )

      (CONNECT_DATA =

        (SERVER = DEDICATED)

        (SERVICE_NAME = cring)

      )

    )'

    create  database link WEIXINDDL connect to WEIXIN_FJ identified by WEIXIN_FJ using 'cring'    

   ---查询服务名称 window

    SHOW PARAMETER service_names

     --查询db_link

     select db_link,owner from dba_db_links for update;

     --删除 dblink

          DROP WEIXIN_FJ LINK WEIXINDL(DBLINK名) ;

     --删除 public dblink

          drop public  database link WEIXINDDL

          --删除  dblink

          drop   database link WEIXINDDL

          --复制表

          Create table tb_name as select * from tb_name@dblink_name;  

          Create table t_em_hb2 as select * from t_em_hb@WEIXINDDL5;  

          insert into tb_name select * from t_em_hb@WEIXINDDL5;

          select count(0) from t_em_hb2;

          select count(0) from t_em_hb;

          select * from t_wechat_red_enve_user_new;

          SELECT * FROM t_wechat_red_enve_user_new@WEIXINDDL link; 

          SELECT * FROM t_wechat_red_enve_user_new@weixinDDL link; 

          ---