When using sqlplus to connect users, ORACLE not available always appears.
first step:
Enter sqlplus
and then enter the user name: sys as sysdba
Enter the password:
Connected to the idle routine.
Step two:
First connect to the administrator user to open the use case
SQL> startup;
ORACLE routine has been started.
Then
Total System Global Area 3390558208 bytes
Fixed Size 2180464 bytes
Variable Size 1979714192 bytes
Database Buffers 1392508928 bytes
Redo Buffers 16154624 bytes
The database is loaded.
The database is already open.
Then you can use it normally
Step 3: How to enable automatic loading of the database
Enter cmd when the server is running, and enter the following code in the command window
1. Edit this instance and change the startup mode to automatic
oradim -EDIT -SID ORCL -STARTMODE auto -SRVCSTART system
2. Edit this instance and change the startup mode to manual
oradim -EDIT -SID ORCL -STARTMODE manual -SRVCSTART system
Description: oradim -EDIT -SID instance name -STARTMODE auto -SRVCSTART system