select * from v_$circuit;查看逻辑回路，共享服务器连接，使用easy connect就会有显示

select * from v_$dispatcher; 一般配置三个

sqlplus 中操作

show parameter dispa

alter system set dispatchers='(PROTOCOL=TCP) (dispatchers=3)'; 这个负责端盘子

alter system set shared_servers=3; 这个负责做菜

show parameter max_dis    max_shared这两个也需要配置下

lsnrctl services 就可以认识到

vim tnsnames.ora

SORCL55 =

  (DESCRIPTION =

    (ADDRESS_LIST =

      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.0.55)(PORT = 1522))

    )

    (CONNECT_DATA =

      (SERVER = shared)        #共享服务器连接，但是这个很慢

      (SERVICE_NAME = orcl.example.com)

    )

  )

s物理视图连接会话

不让1521不能进行共享服务器连接，其他的可以

vim tnsnames.ora

ONLY1521 =

  (DESCRIPTION =

  (ADDRESS = (PROTOCOL = TCP)(HOST = station55.example.com)(PORT = 1521))

 )

 alter system set dispatchers='(PROTOCOL=TCP) (dispatchers=3)(listener=ONLY1521)';

 lsnrctl services  l2 就没有共享服务器连接了，只有1521端口可以连接

 然后进行连接测试,做好tns后会提示12520 TNS error之类4

 在win上的实验

 cmd 

 set ORACLE_SID=orcl

 conn /as sysdba

 show parameter db_name

 show parameter service

 conn hr/hr

 alter user hr identified by hr account unlock;解锁HR用户

 select salary from employees where employee_id=100；

 接下来做数据库链，先去做tns

 vim tnsnames.ora

 ORCL244 =

  (DESCRIPTION =

    (ADDRESS_LIST =

      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.0.244)(PORT = 1521))

    )

    (CONNECT_DATA =

      (SERVER = DEDICATED)

      (SERVICE_NAME = orcl.example.com)

    )

  )

  sqlplus /nolog

  conn hr/oracle_4U      对等

  conn system/oracle_4U  不对等

  create database link dblink1 connect to hr identified by hr using 'ORCL244';创建数据库链

select salary from hr.employees@dblink1 where employee_id=100;

  update hr.employees@dblink1 set salary=8888 where employee_id=100;

  commit;

  然后在去windown上看数据是否被改