Friday, March 28, 2014

DBMS

1. Define database management system?
Database management system (DBMS) is a collection of interrelated data and a set of programs to access those data.
2. List any eight applications of DBMS. 
a) Banking
b) Airlines
c) Universities
d) Credit card transactions
e) Tele communication
f) Finance
g) Sales
h) Manufacturing
i) Human resources
3. What are the disadvantages of file processing system? 
The disadvantages of file processing systems are
a) Data redundancy and inconsistency
b) Difficulty in accessing data
c) Data isolation
d) Integrity problems
e) Atomicity problems
f) Concurrent access anomalies

4. What are the advantages of using a DBMS? 
The advantages of using a DBMS are
a) Controlling redundancy
b) Restricting unauthorized access
c) Providing multiple user interfaces
d) Enforcing integrity constraints.
e) Providing back up and recovery

5. Give the levels of data abstraction? 
a) Physical level
b) logical level
c) view level



6. Define instance and schema? 
Instance: Collection of data stored in the data base at a particular moment is called an Instance of the database.
Schema: The overall design of the data base is called the data base schema.

7. Define the terms 1) physical schema 2) logical schema. 
Physical schema: The physical schema describes the database design at the physical level, which is the lowest level of abstraction describing how the data are actually stored.
Logical schema: The logical schema describes the database design at the logical level, which describes what data are stored in the database and what relationship exists among the data.

8. What is conceptual schema?
The schemas at the view level are called sub schemas that describe different views of the database.

9. Define data model?
A data model is a collection of conceptual tools for describing data, data relationships, data semantics and consistency constraints.

10. What is storage manager? 
A storage manager is a program module that provides the interface between the low level data stored in a database and the application programs and queries submitted to the system. 

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