Some common operations with user account in Oracle database

Connection to SQL Plus

In reality, we have two ways to utilize SQL Plus tool.

Using Termial on Linux or CMD on Windows
- Typing cmd on Window + R dialog
- After that, running command.
```
  sqlplus / as sysdba
```
Open directly SQL Plus
- On Window taskbar, typing the SQL plus and enter it.
- Then, we have SQL plus’s UI like the below image.
- Enter username as sys as sysdba, and password that we type when setting up Oracle database.

According to Oracle’s website, we have the flow for creating user.

Then, we will run the below command.

CREATE USER weblogic123 IDENTIFIED BY weblogic123;

Sometimes, we will encounter a problem like:

The reason why Oracle causes this error is that it need the prefix c## of username.

In order to solve this error, we have two solutions:

Using prefix c## with username

 CREATE USER c##weblogic123 IDENTIFIED BY weblogic123;

Belows are some roles that we need to assign for users.

CONNECT role
RESOURCE role allows a user to create named types for custom schemas.
DBA role allows the user to not only create custom named types, but alter and destroy them as well.

GRANT CONNECT, RESOURCE, DBA TO weblogic123;

Grant a privilege to connect to oracle database

 GRANT CREATE SESSION TO weblogic123;

 GRANT CREATE SESSION GRANT ANY PRIVILEGE TO weblogic123;

Grant a privilege that a user can have a disk space to modify or create tables or data.
```
 GRANT UNLIMITED TABLESPACE TO weblogic123;
```
Grant a privilege for operations with table

To know more about the table privileges, we can refer https://docs.oracle.com/database/121/DBSEG/authorization.htm#DBSEG99919.
```
 GRANT SELECT, INSERT, UPDATE, DELETE, CREATE ON database_name TO username;
```
Grant all privileges
```
 GRANT ALL PRIVILEGES TO weblogic123;
```