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1. What is a Database?
A database is a logically coherent collection of data with some inherent meaning, representing
some aspect of real world and which is designed, built and populated with data for a specific
purpose.
2. What is DBMS?
It is a collection of programs that enables user to create and maintain a database. In other words
it is general-purpose software that provides the users with the processes of defining, constructing
and manipulating the database for various applications.
3. What is a Database system?
The database and DBMS software together is called as Database system.
4. Advantages of DBMS?
Redundancy is controlled. Unauthorised access is restricted. Providing multiple user interfaces.
Enforcing integrity constraints. Providing backup and recovery.
5. Disadvantage in File Processing System?
· Data redundancy & inconsistency.
· Difficult in accessing data.
· Data isolation.
· Data integrity.
· Concurrent access is not possible.
· Security Problems.
6. Describe the three levels of data abstraction?
The are three levels of abstraction:
1. Physical level: The lowest level of abstraction describes how data are stored.
2. Logical level: The next higher level of abstraction, describes what data are stored in
database and what relationship among those data.
3. View level: The highest level of abstraction describes only part of entire database.
7. Define the "Integrity Rules"
There are two Integrity rules.
1. Entity Integrity: States that ?Primary key cannot have NULL value?
2. Referential Integrity: States that ?Foreign Key can be either a NULL value or should be
Primary Key value of other relation.