Newcomer, no points, a great god, please help states
Please enter the user name: Scott/tiger
ERROR:
ORA - 01034: ORACLE not available
ORA - 27101: Shared memory realm does not exist
Yesterday also can enter oracle under DOS with up sqlplus
Can't get into today, with pl/SQL also can't get into what's going on?

CodePudding user response:

First, check your ORACLE_HOME or is set correctly or not.
Second, check whether oracle has started, select the status from v $instances

CodePudding user response:

 -- a sign to see what 
SQL> The alter database open; 

CodePudding user response:

We haven't should be a database

CodePudding user response:

Use the command line tools, use the default SYS user login try
Start the mount state
Then OPEN the
What specific cast error

CodePudding user response:

Didn't up should be a database,

CodePudding user response:

The database instance didn't start up! The command log in as an administrator to up sqlplus and then startup,