Introduction to Database Technology and DBMS
What is Database?

Database is a computer based record keeping system which is used to record ,maintain and retrieve data.It is an organized collection of interrelated (persistent) data.

What is Database Management System (DBMS)?

A Database Management System (DBMS) is a collection of interrelated files and set of programs which allows users to access and modify files. It provides a convenient and efficient way to store, retrieve and modify information. Application programs request DBMS to retrieve, modify/insert/delete data for them and thus it acts as a layer of abstraction between the application programs and the file system.

  • DBMS acts as a layer of abstraction on top of the File system.
  • For interacting with the DBMS we use a Query language called Structured Query Language (SQL)
General Block Diagram

General Block Diagram - DBMS

Difference Between File based Data Storage System and DBMS

Difference Between File based Data Storage System and DBMS

Types of Databases

1. Centralized Database

In Centralized database system, all data is stored at a single site. It offers a great control in accessing and updating data. However failure chances are high because the system depends on the availability of resources at the central site

Example: Think about a banking application which uses centralized database. In this case the data is stored in a common place. Applications running in various banks may communicate to the common database over network to access or insert/update/delete information.

2. Distributed Database

In Distributed Database system, the database is stored on several computers. Computers in a distributed system may communicate with one another through internet/intranet/telephone lines etc. Most of the distributed systems will be geographically separated and managed. Distributed databases can also separately be administered

Example: Think about a banking application which uses distributed database. Bank's head office may be in India where as branch offices may be in United States and United Kingdom. In this case the bank database can be distributed across the branch offices and head office whereas the individual offices are connected through a network.

Distributed Database

Services provided by a DBMS
  1. Data management
  2. Data definition
  3. Transaction support
  4. Concurrency control
  5. Recovery
  6. Security and integrity
  7. Facilities to import and export data
  8. user management
  9. backup
  10. performance analysis
  11. logging
  12. audit
  13. physical storage control
Three layer Architecture

Three layer Architecture

Detailed System Architecture

Detailed System Architecture

  • The external view is how the use views it.
  • The Conceptual view is how the DBA views it.
  • The Internal view is how the data is actually stored.

An example of the three levels

Users of a DBMS

1. Database Administrator (DBA)

DBA takes care of the administrative tasks of DBMS as the name suggests and his major responsibilities are given below.

  • Management of information
  • Liaison with users
  • Enforcing security and integrity rules
  • Database backup and recovery
  • Monitoring database performance

2. Database designers

Database designers design the database components

3. Application programmers

Application programmers write programs to access/insert/update/delete data from/to database by making use of the various database components.

4. End users

End users use DBMS

Advantages of a DBMS
  1. Data independence
  2. Reduced data redundancy
  3. Increased security
  4. Better flexibility
  5. Effective data sharing
  6. Enforces integrity constraints
  7. Enables backup and recovery
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showing 1-2 of 2 comments,   sorted newest to the oldest
2015-02-18 10:28:40 
nice and easy concepts easily understandable thanks!!!
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2014-05-19 23:37:41 
nice and easy concepts easily understandable thanks
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