Skip to main content

Database Management System

Image
By



DBMS: The database management system, is a generalized software system for manipulating databases. It is basically a computerized record-keeping software system; which stores information and allows users to add, delete, change, retrieve and update that information on demand.

ADVANTAGE OF DBMS ARE

1. Minimal data redundancy
2. Program-data independence
3. Efficient data access
4. Improved data sharing
5. Improved data consistency
6. Improved data integrity
7. Improved security
8. Increased productivity of application development
9. Enforcement of standards
10. Economy of scale
11. Balance of conflicting requirement
12. Improved data accessibility and responsiveness

DISADVANTAGES OF DBMS ARE

1. Increased complexity
2. Required of new specialized skilled manpower
3. The large size of DBMS
4. Increased installation and management costs.
5. Need for explicit backup and recovery


  DATA MODELS:  Data model is a mechanism that provides an abstraction for database applications. Data modeling is used to represent entities of interest and their relationship in the database.


TYPES OF DATABASE MODELS ARE:

 1. Record based- further divided into three main parts

     a. Hierarchical data model
     b. Network data model
     c. Relational data model

 2. Object-based data models- further divided into

     a. ER model
     b. Semantic
     c. Functional
     d. Object oriented

 3. Physical data models-further divided into

     a. Unifying model
    b. Frame memory


 HIERARCHICAL DATA MODEL: 

1. Are represented by an upside-down tree. The user perceives the hierarchical database as a           hierarchy of segments.  A segment is equivalent to a file system record type. The relationship between and record forms a hierarchy.

2. A tree may be defined as a set of nodes such that there is one specially designed node called the root node.

Advantage of hierarchical data model:

 a. Simplicity
b. Data sharing: all data hold in a common database model, data sharing becomes practical.
c. Data independence
d. Data integrity

The disadvantage of the hierarchical data model:

 a. Implementation complexity
b. Inflexibility
c. Lack of structural independence
d. No standard
e. Extensive programming efforts


NETWORK DATA MODEL

1. It is a flexible approach to representing objects and their relationships.

2. A unique feature of this data model is its schema, which is viewed as a graph where relationship types are arcs and object types are nodes.

3. In-network data model technology is a relationship is called a set in which each set is composed of at least two record types. 1st record is called owner record type and 2nd called member record types. the connection between the owner and member record is identified by a link to which database designer assigns a set_name. This set name is used to retrieve and manipulate data.

4. In network data model, a member can appear in more than one set and thus may have several owners and therefore it facilitates many (m:m) relationships between the owner and the member.


 RELATIONAL DATA MODEL 

Relational database management originates from the mathematical concept of relation and set theory, it was 1st proposed as an approach to data modeling by Edgar F. Codd of IBM research in 1970. The relational model uses the concept of a mathematical relation in the form of a table of values and its building block.


Labels:

Comments

Post a Comment

Thank you for comment.

Popular posts from this blog

Block Diagram of Computer|| Basic Explanation

By
A typical computer system irrespective of its size, class or type consists of hardware and software, integrated and synchronized together to perform computational work or data processing. Computer anatomy is concerned with the way the various functional units operate and how they connected together to form the computer system. A computer system consists of the following functional units : 1)  Input unit 2) Memory/Storage unit 3) CPU(central processing unit) 4) Output unit
Post a Comment
Read more

Types Of Computer System || Analog Hybrid and Digital Computer System

By
Types of computer There are various methods on which computers can be classified. The classification may depend upon the size, technology, area, of application, type of data processed, etc. Generally, computers are divided into three main parts, These three are followings: Analog computers Hybrid computers Digital computers Analog computers An  analog computer  or  analogous computer  is a form of  computer  that uses the continuously changeable aspects of physical phenomena such as  electrical ,  mechanical , or  hydraulic  quantities to  model  the problem being solved.  Analog computers are computers that work on continuous data. Analog computers are used to measure physical quantities like pressure, temperature, speed, etc. Analog computers were widely used in scientific and industrial applications where digital computers of the time lacked sufficient performance. Analog computers c...
Post a Comment
Read more

Components of Computer System

By
A system is defined as a set of interacting elements, responding to inputs so as to produce outputs. The computer system also consists of the following elements or components. Software Hardware Firmware Humanware   Software All the intangible components of the computer system are known as software In other words, we can say that all computer programs and applications run behind the monitor screen, are known as software. Computer software is a term that describes computer programs. Example   Microsoft-windows (all operating system software) and notepad, MS office suite, window media player(application software). Software is further divided into two parts these are following 1) system software 2) application software Hardware All tangible component of a computer system is known as hardware. In other words, computer hardware is the collection of physical parts of the computer system. Example  CPU(Microprocessor), monitor, keyboard,...
1 comment
Read more