Oracle問題：ORA-12528: TNS: 監聽程序: 所有適用例程都無法建立新連接
問題原始描述：
ORA-12528: TNS:listener: all appropriate instances are blocking new connections
發現問題：
通過在CMD下用lsnrctl status 查看出的問題：發現BLOCKED；
然后：嘗試啟動oracle數據庫：
[root@MyYun ~]# su - oracle
Last login: Thu Jul 18 22:01:58 CST 2019 on pts/1
[oracle@MyYun ~]$ sqlplus / as sysdba
SQL> startup nomount;
ORACLE instance started.
Total System Global Area 1068937216 bytes
Fixed Size 2220200 bytes
Variable Size 394268504 bytes
Database Buffers 666894336 bytes
Redo Buffers 5554176 bytes
SQL> select status from v$instance;
STATUS
------------
STARTED
SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
執行上代碼塊的操作后，在本地使用第三方鏈接工具鏈接Oracle數據庫時就出現了ORA-12528錯誤。
解決辦法如下：
相繼執行如下命令：
[oracle@MyYun~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Thu Jul 18 22:55:06 2019
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to an idle instance.
SQL> shutdown;
ORA-01034: ORACLE not available
ORA-27101: shared memory realm does not exist
Linux-x86_64 Error: 2: No such file or directory
SQL> startup
ORACLE instance started.
Total System Global Area 1068937216 bytes
Fixed Size 2220200 bytes
Variable Size 394268504 bytes
Database Buffers 666894336 bytes
Redo Buffers 5554176 bytes
Database mounted.
exDatabase opened.
SQL> exit;
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
命令解釋：
- shutdown命令： 相當於以下三個命令
normal;
shutdown immediate;
shutdown abort;
- startup命令： 等於以下三個命令
startup nomount;
alter database mount;
alter database open;