1. Windows+R to open the run interface, enter cmd to enter the dos interface, enter the user name and password (correct), and the ORA-12560 error is displayed.
2. Re-enter the user name and password and @ the instance name of the database is the SID of the database
3. That's it, if you want to use sysdba to log in: the command is as follows: sqlplus /@orcl as sysdba
Note : When you log in with the sysdba identity, you cannot query the table created with the scott identity.