【Oracle Database】客户端通过监听器连接数据库实例

服务名  --根据业务需求修改
[oracle@node01 ~]$ sqlplus / as sysdba
SQL> show parameter service_names;
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
service_names                        string      core

实例名  --允许修改不建议修改
SQL> show parameter instance_name
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
instance_name                        string      core

数据库名 --不允许修改
SQL> show parameter db_name
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_name                              string      core

监听器
[oracle@node01 ~]$ cat $ORACLE_HOME/network/admin/listener.ora 
# listener.ora Network Configuration File: /u01/app/oracle/product/11.2.0/db_1/network/admin/listener.ora
# Generated by Oracle configuration tools.
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = node01)(PORT = 1521))   --协议，主机，端口
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
    )
  )
ADR_BASE_LISTENER = /u01/app/oracle

[oracle@node01 ~]$ lsnrctl status
LSNRCTL for Linux: Version 11.2.0.4.0 - Production on 21-AUG-2023 14:09:09
Copyright (c) 1991, 2013, Oracle.  All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=node03)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 11.2.0.4.0 - Production
Start Date                21-AUG-2023 11:05:31
Uptime                    0 days 3 hr. 3 min. 38 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   /u01/app/oracle/product/11.2.0/db_1/network/admin/listener.ora
Listener Log File         /u01/app/oracle/diag/tnslsnr/node01/listener/alert/log.xml
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=node01)(PORT=1521)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521)))
Services Summary...
Service "core" has 1 instance(s).
  Instance "core", status READY, has 1 handler(s) for this service...
Service "coreXDB" has 1 instance(s).
  Instance "core", status READY, has 1 handler(s) for this service...
The command completed successfully

[oracle@node02 ~]$ netca

客户端（本地命名方式）
[oracle@node02 ~]$ cat $ORACLE_HOME/network/admin/tnsnames.ora 
# tnsnames.ora Network Configuration File: /u01/app/oracle/product/11.2.0/db_1/network/admin/tnsnames.ora
# Generated by Oracle configuration tools.
CORE =  --连接字符串（网络服务名）根据业务需求修改
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = node01)(PORT = 1521))  --协议，主机，端口
    )
    (CONNECT_DATA =
      (SERVICE_NAME = core)  --与服务名保持一致
    )
  )

[oracle@node02 ~]$ sqlplus sys/oracle@core as sysdba    --用户名/密码@连接字符串（网络服务名）
SQL> select * from dual;
D
-
X

总结：listener.ora文件中的协议，主机，端口，与通过PMON动态注册的服务名，
与tnsnames.ora文件中的协议，主机，端口，服务名需要保持一致，客户端才可以正常连接数据库服务器。