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Questions and Answers
What is the purpose of the GRANT command in DCL?
What is the purpose of the GRANT command in DCL?
- To permanently delete database objects
- To modify data within a database
- To deny access to users
- To provide specific privileges to users (correct)
Which of the following is a valid usage of the REVOKE command?
Which of the following is a valid usage of the REVOKE command?
- REVOKE DELETE FROM Orders;
- REVOKE INSERT ON Products FROM UserB; (correct)
- REVOKE ALL ON Employees FROM UserC;
- REVOKE SELECT, UPDATE ON Customers TO UserD;
Which privilege allows a user to modify existing data in a database?
Which privilege allows a user to modify existing data in a database?
- SELECT
- INSERT
- UPDATE (correct)
- EXECUTE
What must users have to use GRANT and REVOKE commands?
What must users have to use GRANT and REVOKE commands?
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Which of the following statements about cascading privileges is true?
Which of the following statements about cascading privileges is true?
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Study Notes
DCL Commands and Locks
Grant and Revoke Commands
-
DCL (Data Control Language): Commands used to control access to data in a database.
-
GRANT Command:
- Used to provide specific privileges to users or roles on database objects.
- Syntax:
GRANT privilege_type ON object_name TO user_name;
- Types of privileges:
- SELECT: Allows reading data.
- INSERT: Allows adding new data.
- UPDATE: Allows modifying existing data.
- DELETE: Allows removing data.
- EXECUTE: Allows executing stored procedures.
- Example:
GRANT SELECT ON Employees TO UserA;
- Can grant multiple privileges at once:
GRANT SELECT, INSERT ON Employees TO UserA;
-
REVOKE Command:
- Used to remove specific privileges from users or roles.
- Syntax:
REVOKE privilege_type ON object_name FROM user_name;
- Example:
REVOKE SELECT ON Employees FROM UserA;
- Can revoke multiple privileges at once:
REVOKE SELECT, INSERT ON Employees FROM UserA;
-
Considerations:
- GRANT and REVOKE can be cascaded (affects dependent permissions).
- Users must have appropriate privileges to use GRANT and REVOKE commands.
- Must consider the principle of least privilege to enhance security.
Data Control Language (DCL)
- DCL commands are used to control access to data in a database
Grant Command
- Grants specific privileges to users or roles on database objects
- Syntax:
GRANT privilege_type ON object_name TO user_name; - Privilege types:
- SELECT: allows reading data
- INSERT: allows adding new data
- UPDATE: allows modifying existing data
- DELETE: allows removing data
- EXECUTE: allows executing stored procedures
- Can grant multiple privileges at once:
GRANT SELECT, INSERT ON Employees TO UserA;
Revoke Command
- Removes specific privileges from users or roles
- Syntax:
REVOKE privilege_type ON object_name FROM user_name; - Can revoke multiple privileges at once:
REVOKE SELECT, INSERT ON Employees FROM UserA;
Considerations
- GRANT and REVOKE commands can be cascaded, impacting dependent permissions
- Users must have appropriate privileges to use GRANT and REVOKE commands
- Consider applying the principle of least privilege for enhanced security
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