Data Control Language (DCL)
This is the fourth sub language in SQL contains two commands
CREATE USER<User name> IDENTIFIED BY <Password>
This command is used to giving the privileges and roles to a normal user.
It can be defined as permission or a simple command such as Create table, create any table, alter table, alter any table.
It can be defined as collection of privileges or permissions. It can be classified into two types
- System defined roles
- User defined roles
1. System defined roles
A role which is already constructed along with any software those roles can be called as system defined roles.
Connect, resource, dba
2. User defined roles
A role which is defined by user manually those roles can be called as user defined roles.
SQL> show user USER is "SCOTT" SQL> connect as sysdba Enter user-name: sysdba Enter password: Connected. SQL> show user USER is "SYS" SQL> create user ashok identified by kumar ; User created.
grant role1, role2, privilliege1, privilliege2,——–,grant n, privilege n to <user name>
grant connect to ashok; grant resource to ashok;
To give permission to access other user data
grant select on scott.emp to ashok; rant update, delete,insert on scott.emp to ashok; grant all on scott.emp to ashok;
This command is used to take back the permissions from a normal user.
revoke all on scott.emp from ashok; Grant privileges create INDEX, VIEW, and SYNONYM: Grant create any index to SCOTT; Grant succeeded. Grant create any view to SCOTT; Grant succeeded. grant create materialized view to scott; Grant Create any Synonym to scott; Grant succeeded.
Here any means we can create particular database object on any user account.
Syntax for password change Changing password for Ashok Old password: ashok New Password: Ashok143 Syntax to see the list of privileges Select * from session_privs; To see the users Select * from dba_users To show user_id Select * from dual; To lock account Alter user Ashok account lock/unlock; Syntax to drop user account Drop user username cascade; Drop user Ashok
If user account contains no data we need not to cascade otherwise cascade.