RDBMS

Created Feb. 7, 2024 by Archana kalia

Database Examples

Database is involved like everywhere in our world

 For example: If we go to bank to deposit or withdraw, Make hotel and airline reservation, Purchase something on line, Buy groceries in supermarkets

Database Applications

 These examples are what we called traditional database applications

  More Recent Applications:

  •  You tube
  •  iTunes
  •  Geographic Information Systems (GIS)
  •  Data Warehouses
  •  Many other applications

Database can be any size and complexity

Database System

 Database:   A collection of related data.

 Data: Known facts that can be recorded and have an implicit meaning.

 Database Management System (DBMS): A software package/system to facilitate the

              Define, Construct, Manipulate and Share functions of a computerized database.

Typical DBMS Functionality

  • Define a particular database in terms of its data types, structures, and constraints
  • Construct or Load the initial database contents on a secondary storage medium
  • Manipulate the database:

                      Retrieval: Querying, generating reports

                       Modification: Insertions, deletions and updates to its content

                        Accessing the database through Web applications

  •  Share a database allows multiple users and programs to access the database simultaneously

Database System: DBMS + Database

Database V.S. File

 In the database approach, a single repository of data is maintained that is defined once then accessed by various users.

The major differences between DB and File are:

  1. Self-describing of a DB
  2. Insulation between programs and data
  3. Support of multiple views of the data 
  4. Sharing of data and multiuser transaction processing

Self-describing nature of a database system

  •  Database system contains not only the database itself but also a complete definition of the database structure and constrains
  •  The information stored in the catalog is called Meta-data (data about data), and it describes the structure of the primary database.   

Insulation between programs and data

  •  In file processing, if any changes to the structure of a file may require changing all programs that access the file
  •  In database system, the structure of data files is stored in the DBMS catalog separately from the access program
  •  This is called program-data independence

Support of multiple views of the data

  • Each user may see a different view of the database, which describes only the data of interest to that user
  •  It may also contain some virtual data that is derived from the database files but it is not explicitly stored

Sharing of data and multi-user transaction processing

  •  Allowing a set of concurrent users to retrieve from and to update the database.
  •  Concurrency control within the DBMS guarantees that each transaction is correctly executed or aborted
  •  For example, when several reservation clerks try to assign a seat on an airplane flight
  • (These types of applications are generally called online transaction processing (OLTP))

Controlling Redundancy

  •  Controlling Redundancy is one of most important feature to use DBMS
  •  The traditional file approach, each group independently keeps their own file.
  •  For example: accounting office keeps data on registration and billing info; whereas the registration office keeps track of registration, student courses and grades. 

Other Advantages of using the DBMS approach

  • Restricting unauthorized access to data
  • Providing Storage Structures (e.g. indexes) for efficient Query Processing
  • Providing backup and recovery services
  • Providing multiple interfaces to different classes of users
  • Representing complex relationships among data

Disadvantages :

• It increases opportunity for person or groups outside the organization to gain access to information about the firms operation.

• It increases opportunity for fully training person within the organization to misuse the data resources intentionally.

• The data approach is a costly due to higher H/W and S/W requirements.

• Database systems are complex (due to data independence), difficult, and time-consuming to design.

• It is not maintain for all organizations .It is only efficient for particularly large organizations.

• Damage to database affects virtually all applications programs.

• Extensive conversion costs in moving form a file-based system to a database system.

• Initial training required for all programmers and users.

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