ORA-xxxx solution encountered when learning Oracle

If you need to view the general meaning of the error, run the following command:

[plain] [root@localhost ~]# su - oracle  [oracle@localhost ~]$ oerr ora 01507  01507, 00000, "database not mounted"  // *Cause:  A command was attempted that requires the database to be mounted.  // *Action:  If you are using the ALTER DATABASE statement via the SQLDBA  //           startup command, specify the MOUNT option to startup;  //           else if you are directly doing an ALTER DATABASE DISMOUNT,  //           do nothing; else specify the MOUNT option to ALTER DATABASE.  //           If you are doing a backup or copy, you must first mount the  //           desired database.  //           If you are doing a FLASHBACK DATABASE, you must first mount  //           the desired database.  [oracle@localhost ~]$  

 

ORA-04043: Enter the following command: desc dictionary; error: ORA-04043 object dictionary does not exist. Solution: alter system flush shared_pool; an error is reported when connecting to the database in SQL Developer. The main cause is that the system cannot start properly due to incorrect parameter values:

[SQL] Microsoft Windows [version 6.1.7601] Copyright (c) 2009 Microsoft Corporation. All rights reserved. C: \ Users \ Administrator> sqlplus/as sysdba SQL * Plus: Release 11.2.0.1.0 Production on Saturday September 28 10:54:02 2013 Copyright (c) 1982,201 0, Oracle. all rights reserved. already connected to the idle routine. SQL> startup ORA-00844: Parameter not taking MEMORY_TARGET into account ORA-00851: SGA_MAX_SIZE 3154116608 cannot be set to more than MEMORY_TARGET 2550136832. -- when this problem occurs, the sga_max_size in spfile is modified before, and this value is greater than memory_target. -- therefore, the parameter value in spfile must be modified, but the system cannot start, so here we create pfile through spfile, -- then modify the value of pfile, then create spfile by pfile, and then restart SQL> create pfile = 'C: \ pfile. ora 'from spfile; the file has been created. SQL> edit c: \ pfile. ora SQL> create spfile from pfile = 'C: \ pfile. ora '; the file has been created. SQL> startup nomount; the ORACLE routine has been started. Total System Global Area 2137886720 bytes Fixed Size 2177456 bytes Variable Size 989857360 bytes Database Buffers 1140850688 bytes Redo Buffers 5001216 bytes SQL> alter database open; alter database open * 1st row error: ORA-01507 :?????? SQL> shutdown immediate; ORA-01507 :?????? The ORACLE routine has been disabled. SQL> startup; the ORACLE routine has been started. Total System Global Area 2137886720 bytes Fixed Size 2177456 bytes Variable Size 989857360 bytes Database Buffers 1140850688 bytes Redo Buffers 5001216 bytes Database load is complete. The database has been opened. SQL>