Saturday, 26 April 2014

Important Interview Questions Of DBMS Most Asked

Important Interview Questions Of DBMS Most Asked
Important Interview Questionsw

1. What is DBMS?

It is a collection of programs that enables user to create & maintain a database.
In other words it is general-purpose software that provides the users with the processes of
defining, constructing & manipulating the database for various applications.

2. What is Database?

A database is a logically coherent collection of data with some inherent meaning,
representing some aspect of real world & which is designed, built & populated with
data for a specific purpose.

3. What is a Database system?
The database & 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 & 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: Physical level: The lowest level of abstraction describes how data are stored. Logical level: The next higher level of abstraction, describes what data are stored in database & what relationship among those data. View level: The highest level of abstraction describes only part of entire database.

7. Define the "integrity rules"
135 There are two Integrity rules. Entity Integrity: States that "Primary key cannot have NULL value" Referential Integrity: States that "Foreign Key can be either a NULL value or should be Primary Key value of other relation.

8. What is extension & intension in DBMS?
Extension - It is the number of tuples present in a table at any instance. This is time dependent.
Intension - It is a constant value that gives the name, structure of table & the constraints laid on it.

9. What is System R? What are its two major subsystems?
System R was designed & developed over a period of 1974-79 at IBM San Jose
Research Center. It is a prototype & its purpose was to demonstrate that it is possible to
build a Relational System that can be used in a real life environment to solve real life
problems, with performance at least comparable to that of existing system.
Its two subsystems are Research Storage System Relational Data System.


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