1. What is the advantage of Database Management System over File Management System?
The advantage of Data Management System over File Management System are:
i. Data independence
ii. Data integrity and security
iii. Efficient data access
2. What is data independence?
Data independence is an ability to modify a schema definition in one level without affecting schema definition in higher level. It is basically used for cost saving. There are two types they are:
i. Physical data independence
ii. Logical data independence
3. What is aggregation?
The process by which entities are combined to form a single entity that creates a relationship between the entities.
4. Define nested queries with example.
Nested query is a query within another SQL query and embedded within the WHERE clause. It is also known as Sub query or Inner query.
SELECT c_id, name, address FROM customer
WHERE c_id IN
(SELECT c_id FROM order);
5. What are the roles of DBA?
The roles of DBA are:
i. Schemas definition
ii. Storage structure and access method definition
iii. Schema and physical organization modification
iv. Granting authorization of data access
v. Routine maintenance
6. What is trigger?
A process which executes automatically to the response of the specific changes such as insertion, deletion or updating when the condition strike.
7. List anomalies of bad RDBMS designs.
The anomalies are:
i. Insert anomaly
ii. Delete anomaly
iii. Update anomaly
8. What is database authentication and authorization?
Database authentication is validating the identity of the user who is accessing the database.
Database authorization is controlling the operation user can perform. It is basically done for securing database system.
9. At what condition database conflict occurs.
The database conflict occurs when:
i. Both variable belong to different transaction.
ii. Two or more transaction access the same data.
iii. At least one of the operation is write operation.
10. Define serializability property of schedule.
It transforms non-serial schedule to serial schedule.
It prevents from data collision.