After Oracle is installed, forget the user name or password + create a new Login User

The username and password used for installing Oracle are not remembered.
 
Don't worry. Open sqlplus.
 
Follow these steps to create a login user:
 
Step 1: Use sys to log on to sys/password as sysdba. Any character of the password can be logged on.
 
Sys/manager as sysdba
 
After successful login, you can create a new user.
 
Step 2:
 
Create user
 
Syntax:
 
Create user Username identified by password create user diway identified by diwaycom;
 
UNLOCK the new USER: alter user Username account unlock/LOCK
 
Alter user diway account unlock; // unlock the user
 
Alter user diway account lock; // user lock
 
Grant New Login User Creation permission
 
Syntax: crant create session to user name
 
Grant create session to diway;
 
Grant new user database administrator permissions
 
Syntax:
 
Crant dba to user name; grant dba to diway
 
'
 
Switch to the newly created user login
 
Syntax: CONNECT user name/Password
 
Connect diway/diwaycom
 
Delete a user
 
Syntax: drop user Name
 
Drop user diway;
 
Note that all operations must be completed with ";" at the end of the operation.