做專案的時候一直報ORA-12520的錯誤，故更改oracle的連線數：

sqlplus sys/manager as sysdba

select COUNT(*) from v$process

select value from v$parameter where name = 'processes';

alter system set processes = 500 scope = spfile;

結果oracle啟動不了了

啟動oracle時：
SQL> startup
ORA-27154: post/wait create failed
ORA-27300: OS system dependent operation:semids_per_proc failed with status: 0
ORA-27301: OS failure message: Error 0
ORA-27302: failure occurred at: sskgpwcr2
ORA-27303: additional information: semids = 132, maxprocs = 20000

以下步驟即可。
1) sqlplus / as sysdba
2) create pfile='d:\pfile.ora' from spfile;
3) 修改d:\pfile.ora中的*.processes引數，比如改成*.processes=500
4）create spfile from pfile='d:\pfile.ora';
5）startup

參考：http://bbs.csdn.net/topics/390237436

以下是重啟資料庫：

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.

SQL> startup;
ORACLE instance started.
Total System Global Area  269554828 bytes
                         Fixed Size   451724 bytes
                        Variable Size   234881024 bytes
                        Database Buffers  33554432 bytes
                        Redo Buffers   667648 bytes
Database mounted.
Database opened.