Tuesday 11 September 2012

DBMS Interview Questions


1.What is a Database?
Ans: A database is a collection of related data .A database is a logically coherent collection of data with some inherent meaning.

2. What is DBMS?
Ans: Database Management system is a collection of programs that enables user to create and maintain a database.
Thus a DBMS is a general purposed s/w system that facilitates the process of defining constructing and manipulating a database for various applications. (Defining a data base involves specifying the data types, structures and constraints for the data to be stored in the data database.
Constructing a data base is the process of storing data itself on some storage medium that is controlled by DBMS. Manipulating a database includes such functions as querying the data base to retrieve specific data, updating the database to reflect the changes in the mini-world.

3. What is a Catalog?
Ans: A catalog is a table that contain the information such as structure of each file , the type and storage format of each data item and various constraints on the data .The information stored in the catalog is called Metadata . Whenever a request is made to access a particular data, the DBMS s/w refers to the catalog to determine the structure of the file.

4. What is data ware housing & OLAP?
Ans: Data warehousing and OLAP (online analytical processing ) systems are the techniques used in many companies to extract and analyze useful information from very large databases for decision making .

5. What is real time database technology?
Ans: These are all the techniques used in controlling industrial and manufacturing processes.

6. What is program-data independence?
Ans: Unlike in the traditional file sys. the structure of the data files is stored in the DBMS catalog separately from the access programs . This property is called program-data independence.i.e. We needn’t to change the code of the DBMS if the structure of the data is changed .Which is not supported by traditional file sys .

7. What is ORDBMS?
Ans: Object oriented RDBMS is a relational DBMS in which every thing is treated as objects. User can define operations on data as a part of the database definition.

8. What is program-operation independence?
Ans: An operation is specified in two parts .
1. Interface (operation name and data types of its arguments).
2. Implementation (the code part)
The implementation part can be changed without affecting the interface. This is called program-operation independence.

9. What is a view?
Ans: A view may be a subset of the database or it may contain virtual data that is derived from the database files but is not explicitly stored .

10. What is OLTP?
Ans: Online transaction processing is an application that involve multiple database accesses from different parts of the world . OLTP needs a multi-user DBMS s/w to ensure that concurrent transactions operate correctly.

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