(m) Security (1) Integrity and (iv) Consistency इकाई-II (Unit-II) उपयुक्त उदाहरण देते हुए किन्हीं चार पर संक्षिप्त टिप्पणियाँ लिखिए- Giving suitable examples, write short notes on any four- (i) Cartesian product. (ii) Relational calculus and relational algebra. (111) Relational model and its use.
Answers
1. Security
2. Integrity
3. Consistency
4. Cartesian product.
Explanation:
Database security refers to the range of tools, controls, and measures designed to establish and preserve database confidentiality, integrity, and availability. It must address and protect the data in the database.
Data integrity in the database is the correctness, consistency and completeness of data.
It is enforced using the following three integrity constraints: Entity Integrity - This is related to the concept of primary keys.
Consistency in database systems refers to the requirement that any given database transaction must change affected data only in allowed ways.
Any data written to the database must be valid according to all defined rules, including constraints, cascades, triggers, and any combination.
Cartesian Product is an operation used to merge columns from two relations. It is never a meaningful operation when it performs alone. However, it becomes meaningful when it is followed by other operations.
It is also called Cross Product or Cross Join